Gen 5 - missing power mystery found?

[Nine Ball]

Two weeks ago, I went to the drag strip in my 2013 Viper. After making the first pass, the car just felt slow the rest of the night. Temps were in the 60s, so weather was actually decent (+400 ft DA) and the car only trapped 120 and 122 on the last two passes. With almost 7,000 miles on this car, I can tell when it isn't pulling as hard as normal. The car began to feel strong again during my drive back home, about 20 minutes into the hour long drive.

So, I had a chat with some lead SRT engineers on the subject. They asked me all sorts of questions about the car, temps, setup, ambient conditions, etc.. When I mentioned the IAT (Intake Air Temperature) readings being high, that got their attention. While starting my car up in the staging lanes, I observed 120-122F IAT readings on the SRT gauge pack application. It was in the 66F range outside, so I knew that wasn't correct. The SRT guys mentioned that the car pulls a lot of ignition timing out of the tune when IAT's exceed 90F. This results in noticeable power loss that you can feel. Compare driving your favorite car on a cool day vs a mid-summer 90F+ day. Some of that performance is due to the cooler air being more dense with oxygen, but a lot of it has to do with the ignition timing being higher also.

Well, I did a little experiment in my driveway today, while washing the car. I decided to start it up and let it idle in the driveway, while I washed it. I figure I was out there 20-25 minutes idling. I did some observations that some might find interesting.

Outside temp (Ambient temperature) was approx 64F
After idling for 10 minutes, the IAT temp reached 71F
After about 20 minutes, the IAT temps were way high. Even though Ambient Temp had not changed.

Compare the digital thermometer showing outside temp, vs what the gauge in the lower right reads. 64F actual, but reading 104F.

http://i466.photobucket.com/albums/rr29/ynotdv8/2013%20Viper/DSC06077.jpg (http://s466.photobucket.com/user/ynotdv8/media/2013%20Viper/DSC06077.jpg.html)

Here is what the Ambient Temp was reading at the very inlet (the filter box is sealed to this opening, it only picks up air from outside the hood).

http://i466.photobucket.com/albums/rr29/ynotdv8/2013%20Viper/DSC06081.jpg (http://s466.photobucket.com/user/ynotdv8/media/2013%20Viper/DSC06081.jpg.html)

Here is what it was reading with the sensor probe stuck in the bottom of the airbox. Not much difference.

http://i466.photobucket.com/albums/rr29/ynotdv8/2013%20Viper/DSC06083.jpg (http://s466.photobucket.com/user/ynotdv8/media/2013%20Viper/DSC06083.jpg.html)

Here is what the gauge was showing at the same time:

http://i466.photobucket.com/albums/rr29/ynotdv8/2013%20Viper/DSC06082.jpg (http://s466.photobucket.com/user/ynotdv8/media/2013%20Viper/DSC06082.jpg.html)

Then I killed the engine and dried the car off. When I got in to restart and move the car, this is what the IAT was reading:

http://i466.photobucket.com/albums/rr29/ynotdv8/2013%20Viper/DSC06084.jpg (http://s466.photobucket.com/user/ynotdv8/media/2013%20Viper/DSC06084.jpg.html)

So, something is going on with the IAT sensor on these cars. They are picking up some false temp readings, likely from the heat generated inside the engine bay. I'm thinking the sensor body itself is getting heat soaked due to the radiator fans blowing hot air on the external surfaces of the filter box, and they are causing the readings to read far too high. When the computer thinks the car is sucking in 120F temps, it pulls a LOT of timing out to make sure that the engine is safe. This results in the PCM going into a reduced power mode, until it sees enough drive cycles (or miles) to allow the IAT's to go down again. They do drop when the car is driving, but never to actual ambient temps measured within the intake box.

I also experimented with opening the hood during idling. Temps went UP with the hood open, vs closed. Those of you that race, leave the hood shut in the staging lane, or on the dyno. The IAT were reading 111F with the hood shut. With the hood open:

http://i466.photobucket.com/albums/rr29/ynotdv8/2013%20Viper/DSC06079.jpg (http://s466.photobucket.com/user/ynotdv8/media/2013%20Viper/DSC06079.jpg.html)

Now, how do we solve this situation. Insulate the IAT sensors and intake tubes from engine/radiator heat? Relocate the IAT sensor (they are integrated into the MAF sensors, not easy)? Maybe SRT can re-code this issue and offer us a PCM re-flash fix.

Tony

[ViperGTS]

and, nobody found this out so far...I am puzzled!
Dick, where are you when we need you! :confused:

[Nine Ball]

I would suspect the Gen 4 has the same issue, but you guys don't have a gauge to monitor IAT with. Would need an OBD2 real-time scanner to log those.

[ViperSmith]

Damn Tony, good catch. I bet once this is figured out you'll have no issues.

[FLATOUT]

Very interesting Tony, so the Gen 4 reads the IAT differently or has a different sensor? That could make a huge difference in what the ECU is doing with the timing. Makes me wonder if that is why I was able to walk my neighbors Gen V in my gen IV. We had just idled for a long time leaving cars and coffee, where as when I raced your car we had been moving from the time we started the cars.

Very interesting.

[ACRucrazy]

In for info.

[slowhatch]

Very interesting, although it raises the question of how something like this--if this is indeed an issue--could of been overlooked in the validation stages on the engineering side. There's no way the test team wouldn't of noticed the freakishly high IATs, especially when so much testing is devoted to seeing system behavior in varying DAs/temps etc. Their eyes had to of been glued to the timing & fuel trims and IATs. Let us know what the guys in the know say with respect to this. Cool observation though tony.

[Jack B]

Why no oil temp in last pic?

[ACRucrazy]

Below 120 degrees?

[Jack B]

It should be close to coolant temp. That in itself could affect the pcm.


Below 120 degrees?

[eucharistos]

not good with our temperatures

[Nine Ball]

Very interesting, although it raises the question of how something like this--if this is indeed an issue--could of been overlooked in the validation stages on the engineering side. There's no way the test team wouldn't of noticed the freakishly high IATs, especially when so much testing is devoted to seeing system behavior in varying DAs/temps etc. Their eyes had to of been glued to the timing & fuel trims and IATs. Let us know what the guys in the know say with respect to this. Cool observation though tony.

Not sure on that gauge, but the one on the dash near the tach was working fine. Probably something wonky with this SRT Ap.

[ViperSmith]

Tony. Went for a short drive myself today. 52* out.

After 15min of drive my IAT was at 92* standing still. Moving at 35mph it would dip to 80*, back at a standstill it would get back to 92*

I also noticed the oil temp yielded no reading, but on the dash it worked fine and dandy.

So, I am seeing the exact same thing myself.

[VENOM V]

Subscribed. Thanks for diving into this Tony.

[ViperSmith]

Putzing around town again

http://i.imgur.com/Xqhw2Zr.jpg

Dips about 10* when moving. Oil temp is dead as in yours (works in tach)

[Jack B]

My car had the same issue today, the oil temp did not appear in Gauge 2, but, it appeared in Gauge 1 and on the dash. I then went back to Gauge 2, from Gauge 1 and it was working in both dashboards. I had car off/on several times thereafter and it has worked every time in all screens.

[Nine Ball]

Jack, I went for an hour drive today also. The oil temp gauge tends to read zero when the SRT Ap first fires up. When I hit any other button within that ap, and go back to Gauges 2, it works properly.

Today was around 60-64F and my cruising on the highway the IAT would consistently read 18-20F too hot. Whenever I'd go wide open throttle for a gear or two, it would drop 10 degrees. But, still an easy 10-12 degrees too hot, no matter what.

I wish we could get the IAT readings off of the external temp sensor shown on the radio screen.

[Jack B]

I will take a high resolution thermal image of the engine compartment tomorrow and post it. I will put temperature markers at various positions - at the worst, it will be discussion material.

[ACRucrazy]

When and why would the IAT ever be at or near 250 degrees. The way the gauge is laid out its almost like 125 is "normal" (middle)

[slowhatch]

I will take a high resolution thermal image of the engine compartment tomorrow and post it. I will put temperature markers at various positions - at the worst, it will be discussion material.

this will be neat to see

[Newport Viper]

What happened to this?


The new hood features the classic Viper NACA duct cold-air intake that rams cool air to the engine intake. Air temperature is only 10 degrees above ambient at the intake, compared to 50 degrees above ambient on most other vehicles.


http://www.marinochryslerjeepdodge.net/2013-srt-viper.htm




http://www.racecar-engineering.com/wp-content/uploads/2013/06/upvipctc2.jpg

[RTTTTed]

At VOI X the SRT team held a seminar at Milan dragstrip. It rained for our session but the SRT engineers said that when they covered the bottom of the tubes and airbox the engine temps were 18bhp lower during track time. They had planned to install a thin insulated shield under the later Gen 4s because they thought that it wouldn't need megabucks spent on Emissions approval. Since no one has stated that their car came with this, I guess it was too mnay hundreds of thousands of bucks required for emissions approval. Sounds like it would really help you guys out? Heat is good for emissions ...

[Brian GTS]

Interesting....I always wondered why my IAT's seemed rather high. I thought maybe I just didn't understand the reading. I also noticed a performance difference, but I just thought it was my imagination?!?! Maybe not...

[ACRucrazy]

I've seen thermo sheilding in gen IV race cars. Planned on doing it to mine over the winter.

I did similar to my SRT 4 back in '03

702

[ICPREY]

Can you gen V guys log timing?

[Steve M]

I don't have any data to back it up, but I'm thinking the same thing happens in my 2008. When it is hot and I'm sitting at a traffic light, it feels very sluggish. I just got a bluetooth OBD-II scan tool yesterday...I'll see what I can come up with for data.

[Nine Ball]

Can you gen V guys log timing?

No gauge for it, but I'd imagine a real-time OBD2 scanner should show it. That would be interesting to see vs temp.

I like the idea of the thermal wrap, might add that to the bottom surface of the airbox and the two intake tubes near the IAT sensor(s). I'm not sure if there is one sensor, or two. The MAF sensor on each side has 4 wires going into it, figured the IAT was integrated into it.

[Westxsrt10]

Do you really think the intake air is that hot?....I don't think so.

Relocating the air temp sensor closer to the inlet is a common mod on newer Hemi's.

[ViperSmith]

Do you really think the intake air is that hot?....I don't think so.

Relocating the air temp sensor closer to the inlet is a common mod on newer Hemi's.

My guess would be the sensor is very close to the plastic of the intake, which gets pretty hot from the engine heat

[Troublemaker]

Now to access where the heat is coming from and see if it can be blocked or diverted. This does bring up the point of exactly what were the magazines testing? It seems to be very plausible that all of the cars tested were well tested and well warmed up, we're they getting less than what is really there, or a car that was being protected by a sensor reading?

I would be interested to hear SRTs assessment of what is happening. This may not have been something the engineers saw coming, first year production is really the best real world test they could have.

[Viper Specialty]

Hey Guys,

I have noticed the same thing on our Pectel equipped Gen-4. To a similar extent, I have also seen this on the Pectel Gen-2 and Gen-3 cars as well. I believe this is about 50/50 on being caused by ambient heating in the engine bay, and also an imperfect seal between the airbox and hood, causing heated air to be taken into the intake.

[Fatboy 18]

Surely this information needs to get back to the engineers at SRT to look at? I'm amazed they did not notice any of these problems while testing the mules? Or maybe they did!

[Jack B]

Dan

A couple questions:

1. Where is the G4 IAT sensor?

2 Does the G4 have the same MAF sensor.

G5 = Continental PBT GF30 5WK9 7509

[ACRucrazy]

Dan

A couple questions:

1. Where is the G4 IAT sensor?

2 Does the G4 have the same MAF sensor.

G5 = Continental PBT GF30 5WK9 7509

1. The G4 has IAT sensors are in the same location.
2. The MAP part number isn't the same when I looked it up. I don't have it handy, however the G5 MAP sensor showed up as 5.7/6.2 Hemi and I even think some of the 4 cyl cars. It' didnt list 2008-2010 Viper.

[ViperSmith]

I also have to ponder what if the cars that have been in the rags hands have been facing this same issue? Be curious if things change whenever this gets fixed.

[Jack B]

This problem does not manifest itself on a road course. At high speed the IAT will get close to ambient. It is doubtful they did much if any dragstrip testing. However, the SRT engineers had to know this could be an issue.


Surely this information needs to get back to the engineers at SRT to look at? I'm amazed they did not notice any of these problems while testing the mules? Or maybe they did!

[Nine Ball]

1. The G4 has IAT sensors are in the same location.
2. The MAP part number isn't the same when I looked it up. I don't have it handy, however the G5 MAP sensor showed up as 5.7/6.2 Hemi and I even think some of the 4 cyl cars. It' didnt list 2008-2010 Viper.

MAF, not MAP.

MAF = Mass Airflow Sensor
MAP = Manifold Absolute Pressure Sensor

[ACRucrazy]

I know the difference, wasn't aware we had MAF.
I saw a MAP sensor in the back of the manifold.
So that must be what is in the intake tubes? I assumed that was the IAT sensor. Is that a combination of the 2 in that 1 sensor then?

[Viper Specialty]

Dan

A couple questions:

1. Where is the G4 IAT sensor?

2 Does the G4 have the same MAF sensor.

G5 = Continental PBT GF30 5WK9 7509

-IAT sensor is integral to the MAF sensors between the Airbox and Throttle Body. There is one on each side, and they are averaged.

-Yes as far as I know.

-Would have to go grab one, but there would have been no reason to change these.

[Tomball-Dodge]

Tony based on your runs yesterday it appears you don't have a fix. I watched you yesterday making runs and the strangest thing happened when you shifted gears your brake lights came on everytime. Nothing has been determined yet but this appears to be ECU Related? The car did not appear to have any power in your runs..... I will howver congratualte you the 06 looked good, nice runs.

[Viperbob]

I agree.. Thermal shielding is necessary I believe.. now that this has been brought to light...this has bothered me since I got the car that the fans blow right at the airbox, tubes and front of the engine...I was thinking about sheilding before this thread. But now that I see that the IAT are so affected ..Im definitely going to do some shielding..

As far as the oil temp gauge not reading properly on the SRT Ap screen ..I get that blank reading too some times, but also discovered once you go out of that ap and go back in it shows up..so its definitely a glitch in the software ..but I dont think it interfaces with the PCM and causes problems

Anyway..thanks NineBall for your input ,data and testing...this will benefit us all



I've seen thermo sheilding in gen IV race cars. Planned on doing it to mine over the winter.

I did similar to my SRT 4 back in '03

702

[Viperbob]

additionally..if a relocation kit for the IAT sensors could be made..that would be perfect

[SilveRT8]

additionally..if a relocation kit for the IAT sensors could be made..that would be perfect

Yes, a combo IAT relocation / shielding / air box sealing kit

[Viper Specialty]

additionally..if a relocation kit for the IAT sensors could be made..that would be perfect

Not possible in the normal sense. They are integrated into the MAF sensor, and relocating one would alter the readings of the other. It could be done only by locating a comparable sensor, and wiring it externally and separate to the original MAF.

Personally, I would leave it alone and shield/seal the box as best as possible. The IAT's at low air flow ARE actually correct. If Chrysler wanted to really solve the problem, the real answer is having an IAT adder modifier that is based on vehicle speed, so that at low vehicle speeds the IAT correction can be offset to limit its effect.

[ViperSmith]

A bunch of us have reached out to SRT and they want to fix the issue guys, don't worry, it will get fixed.

[ACRucrazy]

I would have to think a computer flash to not pull ass loads of timing at 100 degrees IAT would solve the issue.
If the IAT is truly 10 + over ambient and its just the sensor then changing the way the computer thinks may be an easy fix?

Just thinking out loud.

[Space Truckin]

Yes, a combo IAT relocation / shielding / air box sealing kit

:t1236:

[Jack B]

Dan

have you looked at the kit from Vector Racing, it is for GM, however, it is a kit for a combo MAF/IAT sensor, it intercepts just the IAT leads and allows you to locate it to the front of the car. Everything is plug and play with connectors.



Not possible in the normal sense. They are integrated into the MAF sensor, and relocating one would alter the readings of the other. It could be done only by locating a comparable sensor, and wiring it externally and separate to the original MAF.

Personally, I would leave it alone and shield/seal the box as best as possible. The IAT's at low air flow ARE actually correct. If Chrysler wanted to really solve the problem, the real answer is having an IAT adder modifier that is based on vehicle speed, so that at low vehicle speeds the IAT correction can be offset to limit its effect.

[mjorgensen]

With the fans blowing at hot idle the drivers side is reading 96-98 and because of the fans proximity we are seeing 102-105 so when they are averaged it is already at 100, +/- a degree. Although once you rev the engine and pull cool air in the temps drop pretty good, but I wonder how long it takes seeing the cooler readings before the PCM adds back the power. The horizontal cross brace is also supplying a lot of radiant heat and hold the heat right under the sensors. We are going to try also the shielding of the (thin) underside of the airbox and see if it changes much. I even wonder if they could change/add a upper fan shroud to deflect this blowing hot air down and away from the bottom of the box? Maybe that would be a better fix?

[MtnBiker]

A bunch of us have reached out to SRT and they want to fix the issue guys, don't worry, it will get fixed.

Is this a concern on the Gen IV? Not sure I've noticed it, but I don't run quartermile tracks, just road tracks.

[mjorgensen]

Is this a concern on the Gen IV? Not sure I've noticed it, but I don't run quartermile tracks, just road tracks.

Not sure if the PCM is reacting the same at the same temps on the GenIV, but the boxes and placement is similar so maybe. Yesterday we let this car idle for about 45 min while we did the radio update and during that time with the hood open and 65 degrees in the shop we had the IAT reach 120 degrees indicated on the dash and in realtime on the WiTech. With the hood closed this temp dropped to about 108-109 with the fans blowing (A/C on to make sure they did).

Today I did this just to experiment;
807808809

It is 61 in the shop this morning, but with the coolant temp at 189 and the same scenario as yesterday the hood closed temp after 35 min was 96-98 degrees max. The first 25 minutes of idleing at 186 degree coolant temp and the IAT never went over 84 degrees so heat soak of the airbox was slowed at least with the (crude) insulation.

I left the drain hole open for this and will try again with it closed off and then most of the way closed off to see if this 5/8" hole right under the back of the box makes a big difference.

[Nine Ball]

Good experiment Mark. Cover up the intake tubes, also. At least the area leading into the IAT/MAF and the sensor housings.

[mjorgensen]

Good experiment Mark. Cover up the intake tubes, also. At least the area leading into the IAT/MAF and the sensor housings.

I did shield the undersides, the temps were hot enough outside the box that all the aluminum taps came loose LOL so we are re doing it. When it came loose there was a 10+ degree increase right away. Coolant and oil temps at 199 and 197. When it got hot I put our giant swamp cooler in front and blew 70 degree air in the duct, it did nothing to lower the temps past 104 once things got hot, not exactly moving, but weird it did not help more.

[FLATOUT]

Thanks Mark,

Very interesting.

[virginiavenom]

seems like a very minor problem that should be fixed quickly by SRT. this would fix a lot of the lack luster performance other gen V owners have been experiencing. would be very curious to know if this affects gen IVs as well.

[JonB ~ PartsRack]

I cannot help but wonder what the difference is in the 2-vent GTS hood vs the 6-vent SRT hoods and Gen 4 Hoods....

Its gotta make a diff.....

I attended that same Milan Dragway SRT seminar as RTTTed..... An SRT engineer (name witheld) was tellings us that a 'secret weapon' of sorts was to remove the 6-grills of that SRT10 6-vent hood. (G4) My memory is that 30+% airflow resulted at rest, and gave lower under-hood temps. At speed, the flow was even more significant and also resulted in more DOWNFORCE on the front of the car, since the 'trapped' air was escaping easier upwards and over the windcreen, and not being forced under the car to escape, which would create lift. Lower engine bay temps are a bonus.

Less lift = more downforce....and the flow on the windcreen = more downforce/drag.

Hint: ACR-Xs do NOT sport those hood vent honeycomb grilles. Open vents.

[virginiavenom]

I cannot help but wonder what the difference is in the 2-vent GTS hood vs the 6-vent SRT hoods and Gen 4 Hoods....

Its gotta make a diff.....
good question. that would be very interesting to know. who's got one of each in pretty much stock form in similar climates that can run a few tests?

[mjorgensen]

I cannot help but wonder what the difference is in the 2-vent GTS hood vs the 6-vent SRT hoods and Gen 4 Hoods....

Its gotta make a diff.....

Honestly I don't think it will make a ton of difference Jon. The way the heat is pushed from the radiator to the underside of the box is what does it. Then there is the large drain hole that lets even more heat in. Insulation seems to be helping, but during this testing I found that when the fans are on the temps are rising, BUT when I put a swamp cooler in front and just blow through the grill like you would driving slow the temps actually increased. :confused:

Although I agree that the overall engine bay temps have to be cooler with the 6 vents.

[ACRucrazy]

I cannot help but wonder what the difference is in the 2-vent GTS hood vs the 6-vent SRT hoods and Gen 4 Hoods....

Its gotta make a diff.....

I attended that same Milan Dragway SRT seminar as RTTTed..... An SRT engineer (name witheld) was tellings us that a 'secret weapon' of sorts was to remove the 6-grills of that SRT10 6-vent hood. (G4) My memory is that 30+% airflow resulted at rest, and gave lower under-hood temps. At speed, the flow was even more significant and also resulted in more DOWNFORCE on the front of the car, since the 'trapped' air was escaping easier upwards and over the windcreen, and not being forced under the car to escape, which would create lift. Lower engine bay temps are a bonus.

Less lift = more downforce....and the flow on the windcreen = more downforce/drag.

Hint: ACR-Xs do NOT sport those hood vent honeycomb grilles. Open vents.

I have heard that several times, vents out to help with airflow also resulting in more downforce on the front at speed.

[Steve M]

Is this a concern on the Gen IV? Not sure I've noticed it, but I don't run quartermile tracks, just road tracks.

The Gen 4 uses the same basic radiator and air box positioning, so I'd say that it would. I just don't know how different the PCM calibrations are for Gen 4 vs. 5.

This is the best example I can find...looks like the temps were in the upper 80s to low 90s depending on the time of day he ran these times. Regardless, he was trapping in the 122 range:


http://youtu.be/DzNdctA-acA

[Steve M]

Same car, cooler day (temps in the low 50s according to the video description)...traps in the 129 range:


http://youtu.be/0kp0yjz2jI4

Picking up 7 MPH in 40° cooler air is a LOT of power left on the table in the heat.

[FLATOUT]

Steve M that's just DA affecting the power your seeing. 7Mph is not unheard of from summer to fall/winter times. The timing being pulled is a much bigger issue concern.

[Steve M]

Steve M that's just DA affecting the power your seeing. 7Mph is not unheard of from summer to fall/winter times. The timing being pulled is a much bigger issue concern.

That's the thing though...I don't know how much is the cooler, denser air and how much is the PCM stepping in and pulling timing due to heat soak. I wouldn't be as concerned if I hadn't experienced it myself...there's a long traffic light just before the on-ramp to a section of interstate I frequent. On a hot day (85°-90°), the car will feel fine pulling up to the light, but after leaving it and trying to accelerate on the on-ramp, it feels like I'm pulling a lead weight behind me. "Unimpressive acceleration" are the words that come to mind...

On a cooler day (all it takes is about 10°), everything is just fine and the car pulls just like I think it should.

[Voice of Reason]

Steve M that's just DA affecting the power your seeing. 7Mph is not unheard of from summer to fall/winter times. The timing being pulled is a much bigger issue concern.

I've only experienced a 1-2 mph difference between summer and late fall days at the drag strip in other cars. 7 mph is like the car gaining 70 hp, that's way too much from just denser air.

[Jack B]

You must compare density altitude, not just temp.



I've only experienced a 1-2 mph difference between summer and late fall days at the drag strip in other cars. 7 mph is like the car gaining 70 hp, that's way too much from just denser air.

[FLATOUT]

I've only experienced a 1-2 mph difference between summer and late fall days at the drag strip in other cars. 7 mph is like the car gaining 70 hp, that's way too much from just denser air.

Then you don't race enough. That's not uncommon at all. Experienced it many times in multiple cars, made by different automakers. Not trying to be a jerk but DA can make a massive difference in power.

Look at the trap speeds at Bandamere in Colorado and the trap speeds at MIR or Royal Purple raceway.

[FLATOUT]

You must compare density altitude, not just temp.

Exactly; temp, humidity, barometric pressure, and relative elevation to see level at the tracks location.

[Steve M]

You must compare density altitude, not just temp.

Did some digging:

The 122 MPH run was done on Sep. 18th, 2010: DA ~2,849 ft (worst conditions I could find that day, 91.4°, 46% Humidity, 30.02 baro @ 5:30PM)

The 129 MPH run was done on November 5th, 2010: DA -966 ft (time slip showed 10:58PM, conditions were 41.0°, 81% Humidity, 30.33 baro @ 10:47PM)

Does 7 MPH difference sound about right given -966ft DA vs. 2,849ft DA? If so, then nevermind my example.

[FLATOUT]

Yes sir mostly because the hot day was SOOOOOO bad. I have also raced in DA as low as -1800 feet. You talk about making power :D. Thanks for posting the details of those two days it should help people understand just how much DA plays in trap speed and 1/4 mile potential.



Did some digging:

The 122 MPH run was done on Sep. 18th, 2010: DA ~2,849 ft (worst conditions I could find that day, 91.4°, 46% Humidity, 30.02 baro @ 5:30PM)

The 129 MPH run was done on November 5th, 2010: DA -966 ft (time slip showed 10:58PM, conditions were 41.0°, 81% Humidity, 30.33 baro @ 10:47PM)

Does 7 MPH difference sound about right given -966ft DA vs. 2,849ft DA? If so, then nevermind my example.

[KRATEDISEASE]

Thanks Mark,

Very interesting.

Yes, Very Interesting indeed.

[Jack B]

Anyone can get the DragTimes app, they have a mph calculator/corrector for DA.



Yes sir mostly because the hot day was SOOOOOO bad. I have also raced in DA as low as -1800 feet. You talk about making power :D. Thanks for posting the details of those two days it should help people understand just how much DA plays in trap speed and 1/4 mile potential.

[Jack B]

There was a Gen4 poster that ran a 10.9 at MIR, Nine Ball looked up the DA, it was minus 1500. I used the DragTimes app and compared it to a plus 3500 DA, the ET would have been 11.6 with the same 60' time.


Did some digging:

The 122 MPH run was done on Sep. 18th, 2010: DA ~2,849 ft (worst conditions I could find that day, 91.4°, 46% Humidity, 30.02 baro @ 5:30PM)

The 129 MPH run was done on November 5th, 2010: DA -966 ft (time slip showed 10:58PM, conditions were 41.0°, 81% Humidity, 30.33 baro @ 10:47PM)

Does 7 MPH difference sound about right given -966ft DA vs. 2,849ft DA? If so, then nevermind my example.

[mnc2886]

Same car, cooler day (temps in the low 50s according to the video description)...traps in the 129 range:


http://youtu.be/0kp0yjz2jI4

Picking up 7 MPH in 40° cooler air is a LOT of power left on the table in the heat.

That video is proof that once everything gets ironed out, someone is going into the 10's with a Gen V. Trak-pak car will be 150 lbs lighter with more power. Maybe 10.7?

[Nine Ball]

BTW, I did run my '13 at the track a couple more times on this last Sunday's track rental day. It was very consistent, 11.61 @ 123 and 11.61 @ 122. Temps were warmer outside than my previous visit, about 70F. The car just didn't feel like it was pulling hard, as indicated by the trap speeds. IAT readings were consistently 18-22F hotter than ambient. I did not do any burnouts this time, as I didn't want to upset the ABS system. Just drove around the water box, peeled out, and ran it. Bernie from Tomball Dodge was there, he also noted that my car didn't look like it had full power. Taking it in to the dealership, will let them play with it for a couple weeks since I'll be out of town.

I did manage to beat a C6 Z06 with headers/intake/tune though. :)

Tony

[Jack B]

What were your 60's

[FLATOUT]

What were your 60's

I would guess 1.8's based on his ET and MPH.

[Nine Ball]

What were your 60's

Made 2 back passes in a row, no line at the track since we rented it. IAT's were in the 87-90F range for both. I was able to drive 60 mph down the return road, since nobody else was there. That helped keep the IAT consistent.

Yes, I used to bracket race competitively. The car is dead consistent. But not that fast. I'm not so concerned with the 11.6 ET, as I was just trying to see trap speeds without tire spin. Easy take-offs, zero tire spin, hint of bog (not much). Trap speeds just seem low, especially for a 67-70F day.

http://i466.photobucket.com/albums/rr29/ynotdv8/2013%20Viper/13-slips.jpg (http://s466.photobucket.com/user/ynotdv8/media/2013%20Viper/13-slips.jpg.html)

[Jack B]

To make this interesting I took Nine Ball's time slips and entered them into a spreadsheet. I then took two of my back-to-back runs and put them into the file. The only caveat is that I did not know what the DA was during Nine Ball's runs. I would guess it was probably about 1000.

To give us a benchmark I included my last run this year with my 97 GTS. The GTS is a heads and cam car.

835

[Disturbed]

Has anyone asked SRT why these cars trap speed is so low? I would think that this would also be the case with the Gen 4 as well.

[ACRucrazy]

Wonder what would happen with a tank and some miles on 100 octane.

[ViperSmith]

Has anyone asked SRT why these cars trap speed is so low? I would think that this would also be the case with the Gen 4 as well.
SRT knows of this IAT issue :)

[Disturbed]

Has anyone tried to relocate the sensor to the Airbox? Much like the Gen2? I would think this affects Gen4 as well, or is it just a fen5 thing?

[mnc2886]

SRT knows of this IAT issue :)


I wonder if that's why Ralph has been at the drag strip. His trap speeds he's posted show he's missing no power. I hope see this remedied soon.

[Steve M]

Has anyone tried to relocate the sensor to the Airbox? Much like the Gen2? I would think this affects Gen4 as well, or is it just a fen5 thing?

The Gen 4 and 5 cars have an integrated MAF/IAT combo that resides in the inlet tubes, so we'd need an adapter harness + a stand-alone IAT sensor to accomplish this. To my knowledge, those parts don't exist.

Dan Lesser said it earlier (either in this thread or another), but the correct fix is a bias factor (IAT vs. ECT or something along those lines) of some sort that essentially notes the high IATs, but sees that the car isn't moving and therefore doesn't pull a crapload of timing because of it. I know this bias factor is present in some (if not all) GM PCMs, but I don't know how CC handles it. If that bias factor exists in the current software, then the values need changed to account for this heat soak.

[ViperSmith]

I wonder if that's why Ralph has been at the drag strip. His trap speeds he's posted show he's missing no power. I hope see this remedied soon.

Not sure, he has been pulling good times and hitting some good dyno results.

I think the car will see some new life once this gets fixed and we can get real dyno results pulling in.

[v10tt]

Typically the IAT (Intake Air Temperature) sensor is a thermistor, which basically means it measures air temperature by detecting resistance in the air. It is usually a two wire sensor supplied with a 5 volt reference wire.


As air passes over the sensor the resistance changes. This change in resistance affects the 5 Volts supplied to the sensor accordingly. Colder air causes higher resistance and higher signal voltage & warmer air lower resistance and lower signal voltage. The PCM monitors this change in the 5 Volts and calculates air temperature.

Could a resistor be installed inline in the wire back to the PCM to fake the reading, and keep the IAT below the 90 dg. F mark so the computer never pulls timing?

[v10tt]

http://www.dodgedakota.net/boards/per/8976.html

[viper200plus]

Hi all. My son's 2013 hemi Challenger RT, 6 speed manual with super trak pak, seems to have the same problem. I insulated the IAT sensor with aluminum foil for now. My other son's hemi Charger RT had hi IATs as well. We insulated his IAT sensor, relocated his catch can and removed the plastic baffle on the left side of the radiator to allow more, cooler air into the air box intake area. Helped tremendously!! We live in Las Vegas so air temp is an issue. An OBD II real time scan should provide a diagnosis. At last year's SEMA show, overheard a discussion between an SRT engineer and a K&N rep related to hi intake air temps and perhaps the need for an insulating baffle to keep the air box cooler.

[Viper Specialty]

Typically the IAT (Intake Air Temperature) sensor is a thermistor, which basically means it measures air temperature by detecting resistance in the air. It is usually a two wire sensor supplied with a 5 volt reference wire.


As air passes over the sensor the resistance changes. This change in resistance affects the 5 Volts supplied to the sensor accordingly. Colder air causes higher resistance and higher signal voltage & warmer air lower resistance and lower signal voltage. The PCM monitors this change in the 5 Volts and calculates air temperature.

Could a resistor be installed inline in the wire back to the PCM to fake the reading, and keep the IAT below the 90 dg. F mark so the computer never pulls timing?


Very close. These sensors are NTC, which is a Negative Temperature Coefficient Thermistor. Basically, that means that as the temperature increases, resistance decreases, and vice versa. It has nothing to do with the resistance of air, it has to do with the resistance across the sensor itself. They are referenced 5 volts through a static high ohmic value resistor, and the voltage resulting after the thermistor "pulls down" that value, is a gauge of current temperature at the thermistor, which the PCM interprets as a given temperature.

The answer is yes, though you would not want to do so, as ALL readings, at ALL speeds will be affected- even when correct. It would no longer pull timing even when it SHOULD be doing so.

[Disturbed]

Easy fake it out by wiring in a resistor inline. Start with a 100k ohm veritable just to see where the temp lands at say 60 degrees then measure the resistance. Easy stuff. :-)

[Coloviper]

Right way is to relocate IAT, shield and reprogram accordingly with new real world reference tables. Software compensation only in the ECU through programming compensation is never the correct way to fix it as not enough software can be changed to account for every real world scenario. It fixes one situation, to not work in two other ones.

Interesting as if all the new electronics and logging software built into the Gen V Viper now really helps to diagnose problems like this, which were previously unknown. This is great stuff guys. SRT Engineers, like all engineers, love to troubleshoot and fix problems to make the cars better. I have to believe they would be all over this. Coffee pots on full blast in Detroit! Me feels a power increase free of charge coming.

[Disturbed]

Another option is to use another sensor that outputs the correct resistance the PCM wants. But that's something SRT needs to fix and that could be a year or two.

A quicker fix would be what I recogmended earlier. Just put a resistor on it, tweek it until it outputs the correct temp. Read it, then put in a resistor close to that value.

It's not complicated. Just two cheap $1.00 parts, some alligator clips, a $10.00 DMM from Walmart (if you don't have one). Tops this would take an hour to do. This allows you to keep the factory sensor in its current place its just sending the PCM the info it really needs.

[Viper Specialty]

Another option is to use another sensor that outputs the correct resistance the PCM wants. But that's something SRT needs to fix and that could be a year or two.

A quicker fix would be what I recogmended earlier. Just put a resistor on it, tweek it until it outputs the correct temp. Read it, then put in a resistor close to that value.

It's not complicated. Just two cheap $1.00 parts, some alligator clips, a $10.00 DMM from Walmart (if you don't have one). Tops this would take an hour to do. This allows you to keep the factory sensor in its current place its just sending the PCM the info it really needs.

And what would you propose to do when the sensor is outputting 60*F when the real intake temp is actually 120*F, preventing the PCM from removing timing when it SHOULD be? That will be the result of what you are suggesting. You cannot fix a problem downstream and not expect an issue upstream as a result. The only correct fix is SOFTWARE changes, airbox sealing, and insulation techniques. The sensor isn't reading "wrong", it is reading exactly what it is seeing- and what it is seeing is the problem, not the sensor calibration.

[Disturbed]

And what would you propose to do when the sensor is outputting 60*F when the real intake temp is actually 120*F, preventing the PCM from removing timing when it SHOULD be? That will be the result of what you are suggesting. You cannot fix a problem downstream and not expect an issue upstream as a result. The only correct fix is SOFTWARE changes, airbox sealing, and insulation techniques. The sensor isn't reading "wrong", it is reading exactly what it is seeing- and what it is seeing is the problem, not the sensor calibration.

All that's doing is making the air intake sensor see the "real" temp not the false temp. Currently if its 72 outside and the sensor is reading 92deg its pulling timming it shouldn't.

Now if you correct it like i said if its 92 outside its going to read about 92 not 112. (Temp #'s are just an example of the correction).

If your giving the ECU garbage numbers its going to pull timming early.

In my solution your *still* using the sensor as intended...your just giving it correct info to the ecu vs the wrong info its getting now.

Again, your making it out to be more difficult than it is.

What I'm suggesting is no different than putting in a sensor that outputs the right resistance.

It could be fixed in software, I agree. But it can also be fixed via hardware. Two solutions to the same issue. In this cases, the hardware is the easier fix until SRT fixes it (if they fix it) via software OR HARDWARE and to do that it would be a recall.

Again, keep in mind, I'm not saying your wrong. I'm offering a solution that can be done here and now. Your software solution doesn't work at this time.

[Rocket]

I think what disturbed is suggesting that adding the resistor would correct an approximate amount based on the temperature the sensor is actually seeing. In your example, if the real intake temp was 120*, the sensor would report 160* (hypothetically), and after going through the resistor, the computer would see 120* ???


And what would you propose to do when the sensor is outputting 60*F when the real intake temp is actually 120*F, preventing the PCM from removing timing when it SHOULD be? That will be the result of what you are suggesting. You cannot fix a problem downstream and not expect an issue upstream as a result. The only correct fix is SOFTWARE changes, airbox sealing, and insulation techniques. The sensor isn't reading "wrong", it is reading exactly what it is seeing- and what it is seeing is the problem, not the sensor calibration.

[Jack B]

A couple more points:

1. There is also an ambient temp sensor.

2. The problem is not all about the IAT's static reading, but, more it's dynamic response.

3. The IAT is not reading true air temp due to the location. The following drive the IAT readings away from actual air temp:

A. Heat transfer from the engine side to the IAT body.

B. Heat transfer from the inside of intake tube to the IAT body.

In affect with the car moving at any speed the actual air temp is cooler than indicated. To prove this point I am going to put a thermocouple 1" from the Iat and log the readings


H.



And what would you propose to do when the sensor is outputting 60*F when the real intake temp is actually 120*F, preventing the PCM from removing timing when it SHOULD be? That will be the result of what you are suggesting. You cannot fix a problem downstream and not expect an issue upstream as a result. The only correct fix is SOFTWARE changes, airbox sealing, and insulation techniques. The sensor isn't reading "wrong", it is reading exactly what it is seeing- and what it is seeing is the problem, not the sensor calibration.

[Viper Specialty]

All that's doing is making the air intake sensor see the "real" temp not the false temp. Currently if its 72 outside and the sensor is reading 92deg its pulling timming it shouldn't.

Now if you correct it like i said if its 92 outside its going to read about 92 not 112. (Temp #'s are just an example of the correction).

If your giving the ECU garbage numbers its going to pull timming early.

In my solution your *still* using the sensor as intended...your just giving it correct info to the ecu vs the wrong info its getting now.

Again, your making it out to be more difficult than it is.

What I'm suggesting is no different than putting in a sensor that outputs the right resistance.

It could be fixed in software, I agree. But it can also be fixed via hardware. Two solutions to the same issue. In this cases, the hardware is the easier fix until SRT fixes it (if they fix it) via software OR HARDWARE and to do that it would be a recall.

Again, keep in mind, I'm not saying your wrong. I'm offering a solution that can be done here and now. Your software solution doesn't work at this time.

You are missing the fact that it is reading high.... because the temp IS high. That is the point here. The sensor doesn't lie- it is pulling in heat soaked air at low flow, with no timing correction factor for the car not moving. The sensor isn't doing anything that it should not be doing. Your solution will skew the readings in the WRONG direction once the car is MOVING.

Everyone is looking at this problem from the completely incorrect viewpoint. The sensor isn't wrong, nor is its location to operate correctly. The car SETUP is wrong with regard to heat getting where it shouldn't be in the first place. The correction table for SPEED is not currently in the software. If those changes were made, this is a moot problem. Hell, I wouldn't even call it a problem- you are trying to correct something that is already working CORRECTLY.

And you are right- my software solution wont work at this time. SRT would need to implement that. However, correcting something that isn't actually wrong is not the safest approach to fixing this problem either. The correct fix that can be done without SRT is to better assure that only COOL air gets into the airbox, and to prevent heat soaking through the intake components from the fan with insulation. That would prevent the actual problem, without a band-aid solution that is technically incorrect.

[FLATOUT]

You are missing the fact that it is reading high.... because the temp IS high. That is the point here. The sensor doesn't lie- it is pulling in heat soaked air at low flow, with no correction for the car not moving. The sensor isn't doing anything that it should not be doing. Your solution will skew the readings in the WRONG direction once the car is MOVING. Everyone is looking at this problem from the completely incorrect viewpoint. The sensor isn't wrong, nor is its location to operate correctly. The car SETUP is wrong. The correction table for SPEED is not currently in the software. If those changes were made, this is a moot problem. Hell, I wouldn't even call it a problem- you are trying to correct something that is already working CORRECTLY.

This is what I am thinking. It's reading exactly what temps it's seeing you guys need to find a way to cool that airflow not change the sensor reading it.

This is why I was interested in sheilding the housings with some sort of reflective tape or finding a way to redirect the hot airflow away from the intake tubes.

[Viper Specialty]

I think what disturbed is suggesting that adding the resistor would correct an approximate amount based on the temperature the sensor is actually seeing. In your example, if the real intake temp was 120*, the sensor would report 160* (hypothetically), and after going through the resistor, the computer would see 120* ???

And again, you are confusing what "REAL" is. That temp sensor is actually that hot. That is a result of Heat Soak and the intake pulling in fan-heated airflow. There is nothing "wrong" with what the sensor is reading. The calibration IS NOT incorrect. The setup that is causing that sensor to see elevated temps in the first place is what is wrong.

[Viper Specialty]

A couple more points:

1. There is also an ambient temp sensor.

2. The problem is not all about the IAT's static reading, but, more it's dynamic response.

3. The IAT is not reading true air temp due to the location. The following drive the IAT readings away from actual air temp:

A. Heat transfer from the engine side to the IAT body.

B. Heat transfer from the inside of intake tube to the IAT body.

In affect with the car moving at any speed the actual air temp is cooler than indicated. To prove this point I am going to put a thermocouple 1" from the Iat and log the readings


H.

I have to disagree Jack. The sensor design is specifically set up to minimize heat transfer from surrounding components. The air flow is so low at idle that between the pre-heated air sucked in the airbox from the radiator, and the radiant heating from within the tubes, the airflow REALLY is at that temperature. I have eyed this issue up and down on our Gen-4 car. If you put a temporary "plate" to direct airflow from the radiator away from the tubes, and you put a small fan in front of the car to keep the radiator airflow away from the front of the airbox- the problem nearly stops dead. Its no more complicated than that. Its easier to suck in hot air from the engine bay than pull in cool air from outside the hood. Add that to radiating heat from the compartment, and presto- there is your problem.

[Disturbed]

I think what disturbed is suggesting that adding the resistor would correct an approximate amount based on the temperature the sensor is actually seeing. In your example, if the real intake temp was 120*, the sensor would report 160* (hypothetically), and after going through the resistor, the computer would see 120* ???


Bing-O!!! Just correcting the temp. Think of it as a recalibration of the sensor.

[Viper Specialty]

Bing-O!!! Just correcting the temp. Think of it as a recalibration of the sensor.

... Are you missing the point about the calibration NOT being incorrect in the first place?

[ViperGeorge]

Based on the tests conducted by Mark at Woodhouse it would appear the IAT reading is actually correct. The temp of the air at the sensor is what the IAT sensor is reporting. His primitive insulation lowered the IAT a lot (sounds like an opportunity for a vendor (Dan) to create an insulation kit). The problem appears to be that the airbox is getting heat soaked which in turn heats the air in the intake tubes. Fooling the PCM into thinking the IAT is lower is not the solution. The airbox must be better insulated from engine/radiator heat which would actually lower the temperature of the air. Keeping timing when the air is actually hot is a profoundly bad idea. Of course I will change my view if someone posts the temp readings off of an independent temp probe inserted into the intake tube at the same location of the IAT sensor that shows the IAT sensor is wrong.

[Viper Specialty]

Of course I will change my view if someone posts the temp readings off of an independent temp probe inserted into the intake tube at the same location of the IAT sensor that shows the IAT sensor is wrong.

No need... already have done it. We changed from a Gen-4 type NTC to a Gen-3 type NTC which was calibrated directly on our Pectel system, thinking it may have been a fluke as well [and to get the unused MAF's out of the equation]. Exact same result, on a different sensor, on a known correct and double checked calibration.

[SSGNRDZ_28]

Sounds like insulating the intake components will be at least a partial solution. In the motorsport industry we use the following products:

http://www.thermalprotectioninc.com/Heat_Reflective_Films.html

http://www.hrpworld.com/store/default/silver-reflective-film-per-linear-ft-13864.html

My plan is to use the silver 1503-28 (for aesthetic reasons) on the underside half of the airbox, tubes, and Gen V intake. A full wrap may be more effective but visually undesirable.

Anyone with a Gen V want to try a quick back to back test since you have the convenience of the IAT reading?


Another question - are the smooth tubes better insulators than the OEM tubes?

[Voice of Reason]

Do we really think the air moving through the air box is being heated 20* between the outside ambient temp and the sensor? That seems very high given its a strait shot from the outside. And it gets harder to believe when you consider at highway speeds the air is moving extremely fast. It seems more likely that the plastic housing for the sensor is radiating heat directly on the sensor causing a false high reading. The sensor is hot, not the air.

[Jack B]

It is not that simple, heat transfer is via radiant transfer, conductive transfer and convective transfer. Those films only impact the radiant transfer. As Dan said, the location is the issue. It is compromise due to the fact it is a combination sensor. There are some adhesive films that also have thermal insulation between two radiant barriers, those would be a better choice. However, there is no way to stop conductive heat transfer into the body of the sensor.

As I said before, i am going to drill a 1/8" hole in front of the sensor and drop a thermocouple in front of the IAT. The thermocouple will be floating in the airstream, therefore, it should be partially immune from the extraneous heat. That will tell us quite a bit, however, I think Dan is correct, relocation is the only true solution. I do not think relocation will be that hard.

I did try insulating both IAT's with the high end DEI product and I did not see a big diff. This is a long term winter project.



Sounds like insulating the intake components will be at least a partial solution. In the motorsport industry we use the following products:

http://www.thermalprotectioninc.com/Heat_Reflective_Films.html

http://www.hrpworld.com/store/default/silver-reflective-film-per-linear-ft-13864.html

My plan is to use the silver 1503-28 (for aesthetic reasons) on the underside half of the airbox, tubes, and Gen V intake. A full wrap may be more effective but visually undesirable.

Anyone with a Gen V want to try a quick back to back test since you have the convenience of the IAT reading?


Another question - are the smooth tubes better insulators than the OEM tubes?

[ViperSmith]

Jack, did you get my PM?

[ViperGeorge]

Do we really think the air moving through the air box is being heated 20* between the outside ambient temp and the sensor? That seems very high given its a strait shot from the outside. And it gets harder to believe when you consider at highway speeds the air is moving extremely fast. It seems more likely that the plastic housing for the sensor is radiating heat directly on the sensor causing a false high reading. The sensor is hot, not the air.

You might be right but then Jack B says he insulated the sensors with no effect. How would you explain that?

[Viper Specialty]

Do we really think the air moving through the air box is being heated 20* between the outside ambient temp and the sensor? That seems very high given its a strait shot from the outside. And it gets harder to believe when you consider at highway speeds the air is moving extremely fast. It seems more likely that the plastic housing for the sensor is radiating heat directly on the sensor causing a false high reading. The sensor is hot, not the air.

Its not "think"... its "know". The sensor is not THAT conductive. It is made from plastic, attached to another piece of plastic, and is caging an NTC thermistor that is basically suspended in free air with its attaching point about 2" from its actual measuring surface. That's a long way to conduct a large amount of heat given the constant air flow over the whole sensor. Trust me, these sensor manufacturers understand the ambient heat issue in an engine compartment.

Air flow is moving quite slowly at idle speeds given the volume of the box and tubes. The heat being blown onto the other side of that box and tubes is at least 125* higher even on a 75* day. Heating slow moving air by 20* when it is flowing through parts warmer than that by 6x that amount should not be surprising.

[ViperGeorge]

Its not "think"... its "know". The sensor is not THAT conductive. It is made from plastic, attached to another piece of plastic, and is caging an NTC thermistor that is basically suspended in free air with its attaching point about 2" from its actual measuring surface. That's a long way to conduct a large amount of heat given the constant air flow over the whole sensor. Trust me, these sensor manufacturers understand the ambient heat issue in an engine compartment.

Air flow is moving quite slowly at idle speeds given the volume of the box and tubes. The heat being blown onto the other side of that box and tubes is at least 125* higher even on a 75* day. Heating slow moving air by 20* when it is flowing through parts warmer than that by 6x that amount should not be surprising.

Dan, based on your tests and what you say here, it would seem we need a highly effective insulating kit for the airbox/air tubes. I would buy one for a Gen 4 for sure. When will you have it available. :)

[slitherv10]

This sounds so interesting. I wish I knew what you guys were talking about.

From what I have read why not just put it in a location that does no get direct heat towards it. In front of the airbox no? Or is the map sensor a problem then?

I know I know,,,..shut up slither!

[Nine Ball]

If someone would develop a custom molded foam/foil insulation cover that would fit along the entire underside of the airbox and intake tubes, that would be sweet. We really only need the bottom side protected from the radiator wash.

Or, simple solution. Custom plug-n-play harness to intercept the IAT sensor wires from the MAF/IAT plug and relocate the IAT sensors somewhere inside the front bumper cover, maybe near the grille opening.

Or, SRT re-calibrates the tune to keep the PCM from using idle rpm IAT readings from altering the timing maps. Make it so that timing maps are only set when the PCM sees higher throttle position, say above 75% throttle. That would give a better indication of IAT's, with flow actually coming through the intake. This would be the preferred fix.

[PaulB]

I don't have much to offer in terms of a solution but at least some confirmation. Yesterday I set the SRT Performance app up before I left for work to see if my car was experiencing the high IAT that is being discussed here. I have a 25 minute drive to work and by the time I got to town I saw a 20+ degree delta between ambient and IAT. Once in town and stopping at lights, the IAT was even higher. Obviously this is not isolated to just a few cars but rather it is common to all V's. It just seems so odd to me that SRT did not catch this during their testing and mule trials. Regardless of that, as with most problems there often times is an opportunity for someone. Maybe this is an opportunity for some of the tuners out there to come up with a solution or maybe this is an opportunity for SRT to show their commitment to the car and to V owners who have plucked down major coin for the car. In any event I hope a solution comes soon.

[FLATOUT]

Well this should be a no brainer for our vendor base. Gen 4&5 owners will both be in the market for this product/fix. Since the Gen V guys can monitor the temps via the SRT app we'll know if the temps are reporting lower, and the product working.

[Rocket]

Sounds like we need a "Vipair" type cold air system :rolleyes::rolleyes:

[PaulB]

As opposed to the SRT HotAir system? :D

[Disturbed]

And again, you are confusing what "REAL" is. That temp sensor is actually that hot. That is a result of Heat Soak and the intake pulling in fan-heated airflow. There is nothing "wrong" with what the sensor is reading. The calibration IS NOT incorrect. The setup that is causing that sensor to see elevated temps in the first place is what is wrong.

Dan you are confusing the fix. Yes, it is hot. But if you calibrate it to see "real world" temp vs what it sees now it doesn't matter that it is hot. The PCM is then getting the ACTUAL data it needs.

THE PCM READS RESISTANCE. YOU MAKE MAKE THAT RESISTANCE MEAN ANYTHING YOU WANT.

Is there more than one way to fix this yes. We have choices, software, insulate, relocate, hardware or calibrate. To calibrate would be quick and easy until SRT get a real fix.

On a side note we all know these PCM's are tuned rather conservative to be able to run 91 or compensate and run 87oct. If you live in a state that has 93, you could (in theory) make the PCM read cooler and add a little timming and fuel for a cheap and dirty tune. Not ideal but it would work.

[Coloviper]

Disturbed, the problem is the resistance solution you mention assumes a linear response and the real world situation is not linear. It is a real time response that is like a reverse exponential curve.

In the end, people spent $100k+ on their new car. Why band aid a solution? Fix it right and the problem will go away for ALL scenarios not just low rpm, idle or non-speed runs. Position of the hood vents on GEN IV and both GEN V hoods suggests it creates a vacuum of sir in that spot. Vents towards the back of the hood like older GENs may help.

[slitherv10]

Disturbed, the problem is the resistance solution you mention assumes a linear response and the real world situation is not linear. It is a real time response that is like a reverse exponential curve.

In the end, people spent $100k+ on their new car. Why band aid a solution? Fix it right and the problem will go away for ALL scenarios not just low rpm, idle or non-speed runs. Position of the hood vents on GEN IV and both GEN V hoods suggests it creates a vacuum of sir in that spot. Vents towards the back of the hood like older GENs may help.

Where are those vents on my Gen 2...never noticed them?

[Disturbed]

Disturbed, the problem is the resistance solution you mention assumes a linear response and the real world situation is not linear. It is a real time response that is like a reverse exponential curve.

In the end, people spent $100k+ on their new car. Why band aid a solution? Fix it right and the problem will go away for ALL scenarios not just low rpm, idle or non-speed runs. Position of the hood vents on GEN IV and both GEN V hoods suggests it creates a vacuum of sir in that spot. Vents towards the back of the hood like older GENs may help.


Hey SRT, if your reading this. I think i can fix this in about a week with field testing. I'll do it for free. I typically charge $900/day while on travel but I love the viper so no charge. Just tell me where to pick up the test mule.

Or, I'd be happy to fly up and work on it at your place, again, no charge. I'll even pay for my own hotel and meals. Just pay for the flight.

[Viper Specialty]

Dan you are confusing the fix. Yes, it is hot. But if you calibrate it to see "real world" temp vs what it sees now it doesn't matter that it is hot. The PCM is then getting the ACTUAL data it needs.

THE PCM READS RESISTANCE. YOU MAKE MAKE THAT RESISTANCE MEAN ANYTHING YOU WANT.

Is there more than one way to fix this yes. We have choices, software, insulate, relocate, hardware or calibrate. To calibrate would be quick and easy until SRT get a real fix.

On a side note we all know these PCM's are tuned rather conservative to be able to run 91 or compensate and run 87oct. If you live in a state that has 93, you could (in theory) make the PCM read cooler and add a little timming and fuel for a cheap and dirty tune. Not ideal but it would work.


No, I am sorry, you are the one who is confusing the solution by not understanding the problem correctly. What a few people here including yourself seem to be hung up on is that this is not an ambient air temp sensor. It is supposed to read the temperature of what the engine is actually going to be using for combustion. This is a sensor used to gauge the density of the air for metering purposes. Hell, some manufacturers put these INSIDE the intake manifold instead!

I say again, the calibration is correct- the car is ACTUALLY ingesting hot air. Period. By changing the calibration with a resistor, you are also preventing the PCM from judging the correct temperature when it really SHOULD be pulling timing under higher loads. You cannot just alter the resistance of one particular range; you are going to skew ALL of the readings that sensor sees, under ALL circumstances, even when you do not want it to be.

[Viper Specialty]

If someone would develop a custom molded foam/foil insulation cover that would fit along the entire underside of the airbox and intake tubes, that would be sweet. We really only need the bottom side protected from the radiator wash.

Or, simple solution. Custom plug-n-play harness to intercept the IAT sensor wires from the MAF/IAT plug and relocate the IAT sensors somewhere inside the front bumper cover, maybe near the grille opening.

Or, SRT re-calibrates the tune to keep the PCM from using idle rpm IAT readings from altering the timing maps. Make it so that timing maps are only set when the PCM sees higher throttle position, say above 75% throttle. That would give a better indication of IAT's, with flow actually coming through the intake. This would be the preferred fix.


#1 & 3 would work, #2 falls into the same category as what Disturbed is talking about. The further from the point of combustion the IAT sensor is moved, the less correct it is for its intended duty.

[PaulB]

Viper Specialty, please correct me if I am misunderstanding you... I think what you are saying is that no matter what you tell the PCM by programming it or by changing the resistance value of the sensor thermistor, the fact is that the motor will still be ingesting hot air, and that is bad for performance, period. Even if you tell the PCM not to pull timing,the engine is still being aspirated with hot air.

[Viper Specialty]

Viper Specialty, please correct me if I am misunderstanding you... I think what you are saying is that no matter what you tell the PCM by programming it or by changing the resistance value of the sensor thermistor, the fact is that the motor will still be ingesting hot air, and that is bad for performance, period. Even if you tell the PCM not to pull timing,the engine is still being aspirated with hot air.


Yes... and no. The engine NEEDS to know that it is ingesting hot air for correction of the timing and fueling model. This information always needs to be correct, or the modeling will be wrong, especially for fuel. However, the timing model is done more for safety.

The problem is that if you "fool" or "program out" the problem, you are no longer correcting the strategy in areas where it should be corrected. In essence, it is applying a 2D solution to a 3D problem. The correct solution is to either prevent the hot air intake in the first place, or to have the system "ignore" the massive timing corrections for IAT when below a certain Manifold Pressure [Load], knowing that the timing correction for safety is not needed at low load conditions.

[Disturbed]

Someone bring me a Gen4 or Gen5. I will tap into the Intake with a calibrated medical grade thermistor and read it. There is no way MOVING air is getting heated that much through ABS platic in less than ~2'.

Will it heat up a little sure. But not 20+*F.

Ok I'm done beating this horse. Lets see what fix SRT comes up with. I'm betting software or a new sensor.

[FLATOUT]

You actually make a pretty valid point.




Someone bring me a Gen4 or Gen5. I will tap into the Intake with a calibrated medical grade thermistor and read it. There is no way MOVING air is getting heated that much through ABS platic in less than ~2'.

Will it heat up a little sure. But not 20+*F.

Ok I'm done beating this horse. Lets see what fix SRT comes up with. I'm betting software or a new sensor.

[Viper Specialty]

Someone bring me a Gen4 or Gen5. I will tap into the Intake with a calibrated medical grade thermistor and read it. There is no way MOVING air is getting heated that much through ABS platic in less than ~2'.

Will it heat up a little sure. But not 20+*F.

Ok I'm done beating this horse. Lets see what fix SRT comes up with. I'm betting software or a new sensor.


I cannot grasp for the life of me why it is so hard to comprehend how air would be heated by 20* when it is flowing through 2 feet of ~200* piping, box, and filter at low velocity. Do you REALLY think the air inside the manifold is going to be COOLER than the air before the throttle bodies? Would me putting a sensor into the manifold shut you up? I can do it in about an hour. Care to wait? Why is it SO hard to believe that the sensor is actually correct? Common sense dictates it is. Let the car sit for a couple days, and then compare the IAT to the Ambient sensor before starting the car. Its not rocket science. For Christ's sake, our systems have been calibrated umpteen times just looking for errors, seeing as calibrations are part of my job. I even have calibration sheets for our sensors which agree with everything we test in house, and everything agrees with Chrysler calibrations; which I can and have checked as well. I can check every single piece of data that you speculate on in a matter of minutes at 1000hz resolution and print the data in full color to put on the napkin under my martini if I was so inclined. My job is to understand these systems to the best of my engineering ability, and speculation is not a good trait for executing a proper build on the first try, every time.

I spend my life in technical areas [over a decade now in this market] that virtually nobody else has even stepped foot into, and with more design experience in those technical areas than damn near anyone else in the Viper world, and I still end up arguing moot points with people who have a 3rd grasp at best of what they are talking about, yet absolutely refuse to accept that they may be wrong. Funny how its always the SAME people too... I swear that some people are out to just argue with me rather than actually learn something. I really need to start taking the approach that other tuners use; post the answer, and then walk away. Or, just not bother in the first place and ignore the commentary. I am not the only builder that runs into this problem, but I am one of the stupid ones that allows myself to get sucked into it, primarily because the misinformation floating around makes me twitch.

Carry on... I am done arguing with you on this. If you are so confident that your resistor idea will work, then go for it- you will have no one but yourself to blame when it doesn't solve the problem, and causes other issues you didn't even consider because your understanding of the system is lacking.

[mjorgensen]

"Why is it SO hard to believe that the sensor is actually correct? Common sense dictates it is. Let the car sit for a couple days, and then compare the IAT to the Ambient sensor before starting the car."

Did this just a few days ago and just now, yes it will read ambient.

[Viper Specialty]

"Why is it SO hard to believe that the sensor is actually correct? Common sense dictates it is. Let the car sit for a couple days, and then compare the IAT to the Ambient sensor before starting the car."

Did this just a few days ago and just now, yes it will read ambient.

THANK YOU.

Now can some people stop with the nonsense here? This denying reality crap is getting really old.

[Nine Ball]

My education during the final year of engineering school was centered around compressible flow (air, gas, aerodynamics, heat transfer, etc..) and I would say that the heated ABS plastic would heat up the intake air via convection, but the temperatures would be higher at the boundary layer of flow, nearest the surface of the intake walls. The flow through the open cavity should be a lot less affected. While the IAT may be reading the correct temperature it is currently sensing, it is hard to argue that this temp isn't being affected by the sensor placement, and possibly conduction from how it is mounted. Even at WOT, the IAT only drops about 10 degrees on the gauge, even if it were +30 above ambient to begin with. This simply doesn't make much sense. It could be that our IAT sensors take too long to react to temperature changes, especially with reduction in temperature.

In the end, this is likely still something that could be patched by reflashing the PCM with a newer tune. If not, I'd be okay relocating the IAT sensors to somewhere ambient, because I really only care what that sensor reads during high load, WOT condition. Putting around on the highway, or idling, it doesn't really matter.

[mjorgensen]

The thing to remember is that the heated airbox underside (from the radiator and fans) pushes heat up under the filter, plus there is the 3/4" drain hole that is also allowing 120+ degree air into the bottom of the box all the time to mix with the cooler air drawn in the duct. This pre heated air then passes thought the filter into the "heated" top of the airbox and then through the heated tubes that house the IAT sensors so now you can see why the sensors will NEVER read as ambient.

On the dyno I have seen the start of the run IAT reading 86 at 2300rpm and by the time (with high pressure fan simulating fresh air flow right into the duct) 3300rpm it had dropped to 78 so the air is cooled, but the ambient temp in the shop was 64 degrees when we started.

[Viper Specialty]

My education during the final year of engineering school was centered around compressible flow (air, gas, aerodynamics, heat transfer, etc..) and I would say that the heated ABS plastic would heat up the intake air via convection, but the temperatures would be higher at the boundary layer of flow, nearest the surface of the intake walls. The flow through the open cavity should be a lot less affected. While the IAT may be reading the correct temperature it is currently sensing, it is hard to argue that this temp isn't being affected by the sensor placement, and possibly conduction from how it is mounted. Even at WOT, the IAT only drops about 10 degrees on the gauge, even if it were +30 above ambient to begin with. This simply doesn't make much sense. It could be that our IAT sensors take too long to react to temperature changes, especially with reduction in temperature.

Points:
-Yes, I would agree generally.

-The MAF sensors have a "scoop" design situated close to center, and the sensor is off to the side of the scoop. This would indeed put it outside the realm of the typical boundary layer where the turbulence may be stiring things up a bit at low velocity. Also, the IAT sensor itself does have a decent amount of mass, and will surely be subject to a delay in change internally.

-The sensor is without question software dampened to a moderate degree- also doesn't help the situation.


In the end, this is likely still something that could be patched by reflashing the PCM with a newer tune. If not, I'd be okay relocating the IAT sensors to somewhere ambient, because I really only care what that sensor reads during high load, WOT condition. Putting around on the highway, or idling, it doesn't really matter.

I have to disagree. The IAT is a fundamental component of the fueling model. You want it to read the actual IAT temp at all times.


I still stand by the correct solution to all of this is the same as has been said multiple times. Keep the heat away from the intake, and keep the heated air from the radiator from being sucked into the intake. Simple as that. Without the heat pouring all over everything, the problem in its entirety is erased from existence. You don't fundamentally change a correctly operating system to correct a single unrelated and outside caused issue.

I also think people are overreacting. This problem exists to some extent on ALL cars. Its just that no one had a gauge to see it until now- just one more thing for people to freak out about. LOL

[ViperGeorge]

The following comes directly from a friend of mine at SRT. He's an engineer. -->>

If you sit and idle a car, it will heat soak everything in the engine compartment especially when the radiator fans come on and blow all the hot air in there. When you get moving again, especially with our hood duct directly into the airbox and airflow from motion, things cool back down. These are not false temp readings, which is why efforts to improve it aren’t very effective. This is also why drag racers make a run, open the hood, shut off the engine, and cool things down before the next run, not idle their car with the hood closed. A big, hairy burnout also generates a lot of heat in the engine compartment. 125+F charge air temp affects air density, knock sensitivity, and catalyst temps which is why the engine must derate.

Driving down the highway, charge temp is rarely more than 20F over ambient. Note that at cruise on the highway, the throttles are open so little that not much airflow is passing through the intake system to cool it quickly. At WOT, things cool down quickly, but that is difficult to do on the street. At Willow Springs last week over a 10 lap run, the ambient was 75F and the intake air temp was 84F running on the track with 242f oil temp buy the end of the run.

I think you’ll find most cars and intake systems heat soak much worse than the Viper given our airbox, scoop, and engine compartment venting. You are just not given a gauge to know it. The gauge is there so owners can take the necessary precautions to keep the intake temps down when it matters.

If the radiator is on, it is blowing hot air on the engine, that blows hot air on the intake box and tubes and gets trapped between the intake manifold and block. What is important is that the temp is accurate so that the protection systems can do their job. Tricking the intake temp signal will just increase risk of damage. I don’t know exactly when the derates start coming in heavy enough to make a measurable difference in output that affects vehicle performance to the point of overcoming run to run variation. One of the engine calibration guys will have to answer that. I think insulating material will have a marginal affect at best, though.

Why are the car magazines able to get good times? Because they know you have to let things cool down between runs, not sit there idling, heat soaking everything.

If you drive down the highway in 6th gear an then crack the throttles full open and hold it, the intake temp immediately starts dropping on the gauge. Full throttle with road speed actually cools the charge temp and underhood temps down due to airflow.

[Viper Specialty]

The following comes directly from a friend of mine at SRT. He's an engineer. -->>

I think you’ll find most cars and intake systems heat soak much worse than the Viper given our airbox, scoop, and engine compartment venting. You are just not given a gauge to know it. The gauge is there so owners can take the necessary precautions to keep the intake temps down when it matters.


Irony. That is damn near the same as what I posted just before I saw this new post.

[ViperSmith]

Why does the Gen V have such an issue with this when it is "virtually" the same intake design from the Gen II on up?

I am missing something to why previous generations don't have this issue.

[FLATOUT]

Irony. That is damn near the same as what I posted just before I saw this new post.

Ok so we understand the problem, and if this happens to all cars why is it that the Gen V is losing so much power? Just an issue with what the ECU is doing?

[Viper Specialty]

Why does the Gen V have such an issue with this when it is "virtually" the same intake design from the Gen II on up?

I am missing something to why previous generations don't have this issue.

I can tell you that Gen-4's certainly do, but the "safety" programming may be different on the 5's making it show up sooner on the Dyno. Never paid much attention to it honestly on the older cars, as the Dyno Fans tend to help the issue, and most SC and TT builds are totally different setups with different variables. That said, it is WELL KNOWN that any time you are running a heat-soaked car on the dyno, it absolutely will pick up some decent power when cooled off a bit.

[Viper Specialty]

Ok so we understand the problem, and if this happens to all cars why is it that the Gen V is losing so much power? Just an issue with what the ECU is doing?

I think we all may be jumping the gun. We all know the G5 is a PITA when it comes to dyno'ing. There may be more to this mess than meets the eye so far as what the ECU is doing that we cannot actually see.

That said, it is programming. How aggressive the "safety features" are based on the IAT is certainly SRT's call when they wrote the programming.

[XSnake]

The thing to remember is that the heated airbox underside (from the radiator and fans) pushes heat up under the filter, plus there is the 3/4" drain hole that is also allowing 120+ degree air into the bottom of the box all the time to mix with the cooler air drawn in the duct. This pre heated air then passes thought the filter into the "heated" top of the airbox and then through the heated tubes that house the IAT sensors so now you can see why the sensors will NEVER read as ambient.


The Gen 2 airbox had 3 holes IIRC but they had rubber "nipples" on the end of them to prevent air from being sucked in the bottom. Do the newer gen cars not have these?

[Rocket]

Dan - thanks for the clarification - us keyboard tuners have no where near the experience you do - so it may take us a little while to decipher the information being presented. I was making the assumption that the sensor was getting heat soaked, and thus reading higher than actual airbox temps. If you say it is reading the actual air temp as it passes by the sensor - I would take it as fact. Based on the example, hogwisperer posted, it would seem that in normal driving conditions, the air in the intake is being heated 20 degrees, and in city driving, substantially more. Moving the sensor would be the same band-aid fix as adding a resistor - so it appears that insulating the airbox/tubes is the correct fix as Dan pointed out.

As a side question - if as someone suggested that the stock tune is conservative - would fooling the pcm "a little" by adding a resistor make a difference? For example, if you chose the correct resistor that showed the intake air was 10* cooler than the actual temp - would this provide a small performance gain, while still providing a measure of safety per Dan's example of a real world situation where the air temp was actually 150* (after resistor fool - pcm sees about 140*)

[Viper Specialty]

As a side question - if as someone suggested that the stock tune is conservative - would fooling the pcm "a little" by adding a resistor make a difference? For example, if you chose the correct resistor that showed the intake air was 10* cooler than the actual temp - would this provide a small performance gain, while still providing a measure of safety per Dan's example of a real world situation where the air temp was actually 150* (after resistor fool - pcm sees about 140*)

Its tough to say. Without seeing exactly how the tables are set up in the Venom controller, its like playing a game of darts in the dark. It may be an abrupt change over a certain threshold, it may be a very smooth change, it may be exponential... no way to know how a small change would be dictated. That said, the newer OBD-2 ECU's are purposely "logic checked" every time you start the car. It makes sure that the IAT, ECT, EOT and Ambient sensors are all within a certain percentage of each other, or it can flag a logic error. In the same way, it can prevent you from passing emissions as that data is what the ECU uses to flag a "cold start" cycle.

[mnc2886]

So in other words, there is no fix for this and we won't know if SRT is being ultra conservative until we have the ability to tune (if we ever get it)? I have to say, that is a bit unappealing for the Gen V.

[ViperSmith]

So in other words, there is no fix for this and we won't know if SRT is being ultra conservative until we have the ability to tune (if we ever get it)? I have to say, that is a bit unappealing for the Gen V.

A few of us have been in contact with SRT over this, they'll say something. Patience :)

[Jack B]

Thoughts - why does Ralph's car dyno and trap so high?


I think we all may be jumping the gun. We all know the G5 is a PITA when it comes to dyno'ing. There may be more to this mess than meets the eye so far as what the ECU is doing that we cannot actually see.

That said, it is programming. How aggressive the "safety features" are based on the IAT is certainly SRT's call when they wrote the programming.

[mnc2886]

A few of us have been in contact with SRT over this, they'll say something. Patience :)

This is good to hear. Looks like the good folks here are bringing back constructive Viper discussions that SRT actually would be willing to participate in. This is part of what attracted me to Viper as an adult (everything else got me hooked as a kid). What other car manufacturer asks an owner for feedback and listens? Just one example of this is on the VCA, before the release of the Gen V, there was countless threads stating a want of the return of Gen II styling. There are a number of people that aren't a fan of the styling, and that fine, - to each their own - but we pretty much got what we asked for.

Now, lets get this fixed and start running 10's.

[Viper Specialty]

Thoughts - why does Ralph's car dyno and trap so high?

Interesting thought indeed :)

[mnc2886]

Thoughts - why does Ralph's car dyno and trap so high?

I know you're reaching out to Dan for a technical explanation, but I might add that Ralph might be using his personal car as a test bed secretly. You never know. He did get a build out of SRT's production sequence and very early. Again, just speculating, but as little time and money this car had for development and as pro-active as Ralph is, it might not be a bad idea.

[Coloviper]

Not Viper related but on my 95' Saleen S351R with the 408 stroker and the 12 psi Vortech, to get it to run right at this Colorado altitude, we installed a Moates piggyback chip and relocated the IAT from inside the fender to directly ported into the intake. Required over 19 hrs on the dyno to remap all the tables. It is completely bullet proof now with zero detonation and very little power loss when hot.

It can be done but it must be done right. The big question is why is the IAT not directly ported into the intake already and table maps created for that location? I know a lot of manufacturers do not located it there but it is really where it belongs.

I agree with Dan, that heat should be removed/shielded as that is some of the problem. Given the major issues SRT engineers had in meeting emissions AND making any power increases, ( based upon dinners and discussions with them on high altitude testing of the mules in the Rockies ) I would bet the tune is very emissions friendly and very conservative. With variable valve timing in the cam in cam, it is just a very complicated problem. Heat has always been a a Viper issue.

Hopefully SRT gets after this one as they are most qualified to fix it without upsetting the apple cart in other areas.

[Disturbed]

9-ball gets it!

Until someone taps the manifold at each runner with proper placement of a thermistor you do not know the actual AIT. It's that simple. We can not prove or dis-prove the sensor is right or wrong. That's where it needs to start, not assuming the sensor is right. As the "low power" issue could be something totally unrelated. Simple fact is, we don't know.

I'm thinking SRT knows a thing or two about what is going on and with the venom controller. I would love to have some intelligent technical conversation about the venom controller so I could get some intelligent answers, feedback and data....not assumptions.

I would enjoy analyzing test data and figuring out a better way of doing things for the Viper. SRT you need someone to give you a 3rd set of eyes or just a fresh perspective give me a call. I'm more than happy to help free of charge.

I personally would enjoy seeing a world beating underrated 700hp viper from the factory....that they can't build enough of.

[KRATEDISEASE]

9-ball gets it!

Until someone taps the manifold at each runner with proper placement of a thermistor you do not know the actual AIT. It's that simple. We can not prove or dis-prove the sensor is right or wrong. That's where it needs to start, not assuming the sensor is right. As the "low power" issue could be something totally unrelated. Simple fact is, we don't know.

I'm thinking SRT knows a thing or two about what is going on and with the venom controller. I would love to have some intelligent technical conversation about the venom controller so I could get some intelligent answers, feedback and data....not assumptions.

I would enjoy analyzing test data and figuring out a better way of doing things for the Viper. SRT you need someone to give you a 3rd set of eyes or just a fresh perspective give me a call. I'm more than happy to help free of charge.

I personally would enjoy seeing a world beating underrated 700hp viper from the factory....that they can't build enough of.

Mr. Disturbed,
I know that Mr. Nine Ball is an engineer. I also know that Mr. Viper Specialty is an experienced Viper Tuner with Years of technical experience. ( and may be an engineer or have other qualifications that I am unaware of also).

My question to you is.... what is your background that you are so confident in debating a solution to this issue of the IAT ? I am NOT questioning your formal education. Many people without a formal education are experts in mechanical/engineering problem solving. But what is your knowledge base in cars that gives you the confidence in posting your rebuttals to Mr. Viper Specialty ? This is NOT a challenge question, but just wondering ?

I am NOT defending Viper Specialty. I am just asking what is your background or area of knowledge related to this subject.

Thanks Kratedisease.

[Nine Ball]

Yeah, I don't get the hostility here. We are just trying to have a technical discussion. Not sure what EGO and IAT have in common.

Thanks for all the technical responses, so far. Less drama please, we already have another forum for that.

Tony

[Coloviper]

What would be great is if the VOA could set up a technical webinar with SRT so that technical aspects like this can be discussed, once uncovered. What better way to reconnect with the core customers than to actually connect with them. There are no trade secrets nor future product offering discussions required, just a continued understanding of what people bought. If that is exclusive webinar to the VOA members then even better. A bi-weekly webinar would be awesome.

[v10tt]

I was under the impression that the Calibration was pulling WAY MORE TIMING out of the car after the 90 deg. F. than it was actually needed, making the car very slow. And Pulling timing was the issue, not sensor accuracy.

So thinking that by fooling the computer you could actually run no retard knowing that the stock timing would be fine under actual hot air conditions. Common trick back in the days on GM cars with the IAT relocation kits.

I think insulating the air box is a way of kinda fooling the sensor too. After it goes through the intake tubes, TBs and Intake before the cylinders is going to heat the heck up anyways.

I was under the impression NineBall did not want the car to pull timing at WOT high way speeds. I just don't see Keeping that sensor reading ambient temps inside the engine bay.

[Nine Ball]

The problem is that the Gen 5 seems to lose power after 1 dyno pull. Or, after a single run down the dragstrip. Once it goes into the reduced power (likely lower timing map) it takes several miles or drive cycles to reset to the optimum higher timing map. This isn't feasible when the car is strapped to a dyno, or when the car is waiting in the staging lanes at the track to get another run. Even with the engine shut off and the hood open, the IAT readings are very high upon initial start-up (mine hit 118-120F) after what was supposed to be a cool-down period. This high IAT reading keeps the vehicle in reduced power.

Out on the highway or on the road course, it isn't as affected.

If you want a good run at the dragstrip, you'll have to trailer your car to the track, and then push it by hand to the starting line. That would be the only way to keep the IAT temps at ambient, resulting in highest timing map and power. If you drove the car there, you are probably hosed as soon as you waited to get into the parking area.

[mjorgensen]

From what I have been told the IAT sensor is only one (and a small one) of the parameters that affect the timing of the GenV so any type of "trickery" will likely throw off the logarithms and produce an undesirable affect. The logarithms work with coolant temps, knock sensors and cat conditions also, these are calibrated for worst case scenarios of course being the manufacturer has to account for these conditions.

The Viper may not be set up for the best dyno run or the best drag strip visit, but it is set up for its real intended use, the road course. You can get the best time at the strip with proper cool down, but it will be inconsistent because of all these factors without a repeated cool down, the same with the dyno. The car was built with movement in mind not stationary power measurement and the heat soak associated with the strip. I think we can also, as stated, leave Ralph's car out of the equation for obvious "possible" reasons. I would venture to guess that when Arrow does the dyno testing on the engines they can ignore some of the worst case scenarios, or eliminate the conditions because it is a controlled known environment while measuring total engine output.

[VENOM V]

No question- as Mark stated, it's working fine on the road course. Ever since this issue came up, I've been monitoring my IAT. Temperature was typically less than 20 degrees above ambient while I was at Laguna Seca, which may be about right. I didn't glance at it when I was driving hard at higher speeds, I bet it was on the order of 10 to 15 above ambient. And if the computer was pulling any timing at all, I sure couldn't tell. Nether could the other cars that I would blaze past in the straights. The Gen V pulls very strong.

[ViperSmith]

LOL, I'd imagine Ralphs car is as far from stock as possible.

[Steve M]

Until someone taps the manifold at each runner with proper placement of a thermistor you do not know the actual AIT. It's that simple. We can not prove or dis-prove the sensor is right or wrong. That's where it needs to start, not assuming the sensor is right. As the "low power" issue could be something totally unrelated. Simple fact is, we don't know.

Look at this thread here:

http://driveviper.com/forums/threads/485-Infrared-Pictures-of-Intake-Tubes-and-Air-Box

The temps measured with Jack's IR camera shows that the intake tubes are about as hot as the IAT sensors are reading.

[ViperGeorge]

The problem is that the Gen 5 seems to lose power after 1 dyno pull. Or, after a single run down the dragstrip. Once it goes into the reduced power (likely lower timing map) it takes several miles or drive cycles to reset to the optimum higher timing map. This isn't feasible when the car is strapped to a dyno, or when the car is waiting in the staging lanes at the track to get another run. Even with the engine shut off and the hood open, the IAT readings are very high upon initial start-up (mine hit 118-120F) after what was supposed to be a cool-down period. This high IAT reading keeps the vehicle in reduced power.

Out on the highway or on the road course, it isn't as affected.

If you want a good run at the dragstrip, you'll have to trailer your car to the track, and then push it by hand to the starting line. That would be the only way to keep the IAT temps at ambient, resulting in highest timing map and power. If you drove the car there, you are probably hosed as soon as you waited to get into the parking area.

I thought I would pose this issue to my friend at SRT. Here's what he said:

"Funny I have done dyno pulls two separate times and made MORE power on successive pulls without a big cooldown. Nor does our own drag strip testing match these claims. We did 100 passes down the strip in one day and did not get this phenomenon.

You can try to reflect the heat away. I doubt it will hurt at all. I just don’t think it will have much effect. What you shouldn’t do is fool the IAT temp signal electrically. THAT would cause problems to have a mismatch between the IAT signal temp and the actual air temp."

[Venomous1 Racing]

Guys, I'm a newbie here, but have been tuning fuel injected vehicles since their universal debut in mid- eightys. Dodge, Ford, Chevy, all of them use ambient temps as well as Intake Air Temps to calculate fuel delivery and ignition timing. I have NEVER seen an IAT read ambient temp on a warm engine! While engine is cold, yes, but otherwise its the 20-30* above ambient temps that I've read on cars with data logging software. As mentioned we did truck PCMs by using resistors to fool PCM into thinking its cooler than actual ambient therefore using a higher timing table and not pulling timing. Even my Gen3 Viper Truck has IAT in the CAI elbow as came stock. I've not messed with it but it would seem exposing this sensor closer to NACA Air Duct would effectively drop temps. The problem arises when moisture from rain touches the sensors sensing wire and really throws things in PCM outta whack. If anything it should corrected on the tune via aftermarket or SRT approved update flash.
It'd be nice if the SRT gauge app showed timing pulled. I'll soon datalog a Gen5 and see what's going on and try to help SRT and y'all with a fix. The more info y'all can supply the better.
Scott

[Nine Ball]

I thought I would pose this issue to my friend at SRT. Here's what he said:

"Funny I have done dyno pulls two separate times and made MORE power on successive pulls without a big cooldown. Nor does our own drag strip testing match these claims. We did 100 passes down the strip in one day and did not get this phenomenon.

You can try to reflect the heat away. I doubt it will hurt at all. I just don’t think it will have much effect. What you shouldn’t do is fool the IAT temp signal electrically. THAT would cause problems to have a mismatch between the IAT signal temp and the actual air temp."

Ask him why the cars are triggering stability/traction control codes after doing one dyno pull, even with it disabled on the steering wheel. There have been a couple cases of this already. Then the subsequent dip in horsepower at 5200 rpm on further pulls. That dip in power is likely what is happening at the drag strip, also. My car shouldn't have been trapping 122-123 mph on a 69F day. That would be weak even for a 90F day. Bone stock C6 Z06's were trapping 124-125 in that weather. There is a problem, saying that there isn't won't solve the problem.

[Rocket]

Did anyone ever confirm why the engineers were disconnecting wires on the dyno? Was this to deal with the stability/tc system or possibly to reset other things including the iat sensor?

[Nine Ball]

Did anyone ever confirm why the engineers were disconnecting wires on the dyno? Was this to deal with the stability/tc system or possibly to reset other things including the iat sensor?

Yes, I spoke with Dick Winkles about that video. They were only disconnecting the PCM pigtails in order to plug in their laptop/scanner after making dyno runs, to grab the logged data. They have a harness that plugs right into the PCM. No resets or anything were made. Pulls were made with pigtails connected.

[mjorgensen]

Did anyone ever confirm why the engineers were disconnecting wires on the dyno? Was this to deal with the stability/tc system or possibly to reset other things including the iat sensor?

All they were doing was plugging in a laptop to monitor the engine and other parameters, they did not do anything to change anything, we just did not see the full content and assumed it was something special.

Got me Tony :-)

[ViperGeorge]

Yes, I spoke with Dick Winkles about that video. They were only disconnecting the PCM pigtails in order to plug in their laptop/scanner after making dyno runs, to grab the logged data. They have a harness that plugs right into the PCM. No resets or anything were made. Pulls were made with pigtails connected.

While my friend is a senior engineer with SRT and works on the Viper platform he is not an engine calibration engineer. I'd suggest you try and reach back out to Dick Winkles if you've already been in touch with him. He would probably be able to give a better answer on engine calibration than my friend. My guy does do a lot of the testing on the Viper and he was at the dyno runs in the video.

[ViperSmith]

I am curious to why a few of us are hearing conflicting things from SRT in regards to this issue.

[mjorgensen]

I am curious to why a few of us are hearing conflicting things from SRT in regards to this issue.

In the end there is only one person that knows everything inside and out about this car powertrain wise...

[Viper Specialty]

Mr. Disturbed,
I know that Mr. Nine Ball is an engineer. I also know that Mr. Viper Specialty is an experienced Viper Tuner with Years of technical experience. ( and may be an engineer or have other qualifications that I am unaware of also).


Lets see...

-Schooling for Mechanical Engineering/minor MBA.
-Cosworth Motorsports Electronics Official Dealer/Calibrator
-Original SCT Viper tuner
-Extensive experience in Engine Theory & Engine Building
-Extensive experience in Engine Component Design
-Extensive experience in Engine Management Systems
-Extensive experience in Systems Integration
-Extensive experience in Motorsports Wiring Design & Production
-Extensive experience in SMD Electronics
-Extensive experience in Electronics Retrofit
-Increasing experience in CAN related systems integration and Protocol decoding/development
-Some experience in Software UI Development
-Have assisted multiple companies add/repair/troubleshoot their tuning software, often finding "holes" and inconsistencies in modeling indicating UI issues
-Have designed from scratch or corrected MANY manufactured products
-Have implemented more non-standard solutions than anyone else in this market, bar none
-Have assisted numerous other tuners on proper tuning techniques with regard to narrow-band based engine management system strategies


VSP was the FIRST to (and in many cases only to);
-Produce streetable Tilton Carbon Clutch options
-Successfully run 1000cc+ injectors on a flash tuned OE ECU, passing OBD2 emissions
-Offer forced Piston Oiling on Viper engine builds
-Offer corrected adjustable timing sets for Gen-3
-Convert Gen-4 Oiling systems for Gen3 use- [both Swing Arm pans & full Timing Cover conversions]
-Complete Gen-4 Head Conversion Packages
-Offer True Gen-4 Mechanical Throttle Bodies
-Bring AFM gasket tech to the Gen-1/2 markets
-Bring specialized Head Gasket options to the Viper market
-Retrofit Coil Near Plug Gen-4 system to Gen-3 running on OE ECU
-Complete a running Pectel Gen-4 w/full control
-Integrate a Pectel SQ6M12 in a Viper
-Have OBD-2 compliant Pectel equipped cars
-Integrate a Omega D1 Digital Dash
-Integrate a [Viper Specific] Omega ICD Digital Dash
-Fit a properly working MyGig Infotainment system into a Viper architecture
-Properly solve ALL fuel system inadequacies of the high-flow Viper systems
-Develop corrected differential type fuel pressure/temp regulators


As you can see... we know nothing about automotive technical areas.

[ViperGeorge]

Lets see...

-Schooling for Mechanical Engineering/minor MBA.
-Cosworth Motorsports Electronics Official Dealer/Calibrator
-Original SCT Viper tuner
-Extensive experience in Engine Theory & Engine Building
-Extensive experience in Engine Management Systems
-Extensive experience in Systems Integration
-Extensive experience in Motorsports Wiring Design & Production
-Extensive experience in SMD Electronics
-Extensive experience in Electronics Retrofit
-Increasing experience in CAN related systems integration and Protocol decoding/development
-Some experience in Software UI Development
-Have assisted multiple companies add/repair/troubleshoot their tuning software, often finding "holes" and inconsistencies in modeling indicating UI issues
-Have designed from scratch or corrected MANY manufactured products
-Have implemented more non-standard solutions than anyone else in this market, bar none
-Have assisted numerous other tuners on proper tuning techniques with regard to narrow-band based engine management system strategies


VSP was the FIRST to;
-Produce streetable Tilton Carbon Clutch options
-Successfully run 1000cc+ injectors on a flash tuned OE ECU, passing OBD2 emissions
-Offer forced Piston Oiling on Viper engine builds
-Offer corrected adjustable timing sets for Gen-3
-Convert Gen-4 Oiling systems for Gen3 use- [both Swing Arm pans & full Timing Cover conversions]
-Complete Gen-4 Head Conversion Packages
-Offer True Gen-4 Mechanical Throttle Bodies
-Bring AFM gasket tech to the Gen-1/2 markets
-Bring specialized Head Gasket options to the Viper market
-Retrofit Coil Near Plug Gen-4 system to Gen-3 running on OE ECU
-Have a running Pectel Gen-4 w/full control
-First Pectel SQ6M12 Viper
-Have OBD-2 compliant Pectel equipped cars
-Integrate a Omega D1 Digital Dash
-Integrate a [Viper Specific] Omega ICD Digital Dash
-Fit a properly working MyGig Infotainment system into a Viper architecture
-Properly solve ALL fuel system inadequacies of the high-flow Viper systems
-Develop corrected differential type fuel pressure/temp regulators


As you can see... we know nothing about automotive technical areas.

Dan, great background, but to most of us you have no need to explain your credentials. Speaking for myself the stuff I've bought from you have worked great and were exactly as described. Don't sweat the guys here that question your experience or knowledge for they know not what they are talking about.

[ViperSmith]

Nothing of value in this post.

[Viper Specialty]

I was under the impression that the Calibration was pulling WAY MORE TIMING out of the car after the 90 deg. F. than it was actually needed, making the car very slow. And Pulling timing was the issue, not sensor accuracy.

So thinking that by fooling the computer you could actually run no retard knowing that the stock timing would be fine under actual hot air conditions. Common trick back in the days on GM cars with the IAT relocation kits.

I think insulating the air box is a way of kinda fooling the sensor too. After it goes through the intake tubes, TBs and Intake before the cylinders is going to heat the heck up anyways.

I was under the impression NineBall did not want the car to pull timing at WOT high way speeds. I just don't see Keeping that sensor reading ambient temps inside the engine bay.

The problem is actually being overstated and confused here. This is not a steady-state problem. If you are idling at low load, no problem. If you are cruising down the highway, no problem. This is a transitional issue. The sensor is getting warm, and when you mash the gas, it takes time for the sensor value to correct as the intake air temp actually drops. As a result, you will lose power [timing] until everything stabilizes. By moving the sensor, you will cause it to read wrong during the time periods where it actually is sucking in warm air, and this will affect fuel control among other things.

I would agree with you that the air is going to continue to warm as it reached the cylinder, but fueling strategies are produced with the sensor in a particular placement, so that difference is accounted for in the calibration during actual tuning of the system. This is why altering the signal or moving the sensor is not a good idea. You are sacrificing a correctly operating system overall for a single occurrence that occurs in a single non-standard situation. The solution is to fix ONLY that situation through software, or, to prevent the issue from occurring in the first place.

[Viper Specialty]

Ask him why the cars are triggering stability/traction control codes after doing one dyno pull, even with it disabled on the steering wheel. There have been a couple cases of this already. Then the subsequent dip in horsepower at 5200 rpm on further pulls. That dip in power is likely what is happening at the drag strip, also. My car shouldn't have been trapping 122-123 mph on a 69F day. That would be weak even for a 90F day. Bone stock C6 Z06's were trapping 124-125 in that weather. There is a problem, saying that there isn't won't solve the problem.

My guess is that there is a "Failure timer" on the front wheel speed sensors. Normally, you would get some signal from them all the time, as long as the car is actually moving. The dyno may be long enough to set these errors. If that is indeed the issue, they need to delete that error from the system while in "OFF" mode. Still odd in any event, I have a feeling there is more to it- I cannot see them overlooking that one.

[Viper Specialty]

Dan, great background, but to most of us you have no need to explain your credentials. Speaking for myself the stuff I've bought from you have worked great and were exactly as described. Don't sweat the guys here that question your experience or knowledge for they know not what they are talking about.

Thanks- much appreciated.

[PaulB]

With all due respect, Mark, many of us are drag racers. Discounting folks who intend on using the car for drag racing (or street racing) would be a mistake. After all, SRT is trying to sell more Vipers, not fewer. I never saw any disclosure stating that the V could only be used effectively for road racing. As much as I respect your knowledge and opinion, I have to hope that your position does not reflect SRT's position on this issue.


From what I have been told the IAT sensor is only one (and a small one) of the parameters that affect the timing of the GenV so any type of "trickery" will likely throw off the logarithms and produce an undesirable affect. The logarithms work with coolant temps, knock sensors and cat conditions also, these are calibrated for worst case scenarios of course being the manufacturer has to account for these conditions.

The Viper may not be set up for the best dyno run or the best drag strip visit, but it is set up for its real intended use, the road course. You can get the best time at the strip with proper cool down, but it will be inconsistent because of all these factors without a repeated cool down, the same with the dyno. The car was built with movement in mind not stationary power measurement and the heat soak associated with the strip. I think we can also, as stated, leave Ralph's car out of the equation for obvious "possible" reasons. I would venture to guess that when Arrow does the dyno testing on the engines they can ignore some of the worst case scenarios, or eliminate the conditions because it is a controlled known environment while measuring total engine output.

[pdv25]

With all due respect, Mark, many of us are drag racers. Discounting folks who intend on using the car for drag racing (or street racing) would be a mistake. After all, SRT is trying to sell more Vipers, not fewer. I never saw any disclosure stating that the V could only be used effectively for road racing. As much as I respect your knowledge and opinion, I have to hope that your position does not reflect SRT's position on this issue.

+1...

[Newport Viper]

With all due respect, Mark, many of us are drag racers. Discounting folks who intend on using the car for drag racing (or street racing) would be a mistake. After all, SRT is trying to sell more Vipers, not fewer. I never saw any disclosure stating that the V could only be used effectively for road racing. As much as I respect your knowledge and opinion, I have to hope that your position does not reflect SRT's position on this issue.

No more drag racing at VOI's then?

[99RT10]

No more drag racing at VOI's then?


Ha! What VOI's? You mean VOA-I? ;)

[Jack B]

How about this, I have lined up againt vettes approx 20 times with my G2. Think of the impact on the people in the stands to see a viper always put 5-10 cars on america's super car.

Multiiply that by all of us drag racers, that is good pr.

[mjorgensen]

With all due respect, Mark, many of us are drag racers. Discounting folks who intend on using the car for drag racing (or street racing) would be a mistake. After all, SRT is trying to sell more Vipers, not fewer. I never saw any disclosure stating that the V could only be used effectively for road racing. As much as I respect your knowledge and opinion, I have to hope that your position does not reflect SRT's position on this issue.

It's ok that you disagree, I get it, but the reality is that you generally have to compromise one for the other (road course or drag race unless of course you are talking AWD). And you are correct in assuming that the statement was all mine not SRT's, but on the other hand you see SRT going for track records with the Viper a lot more then talking about the 1/4 mile don't you?

I was not trying to alienate any of you, I think the Viper is a blast for either one and I have done extensive amounts of Pro Solo (drag race .500 tree that turns into mirror image autocross courses) with my old black/red Viper.

https://www.youtube.com/watch?v=gxg4CJCgynM

[ViperGeorge]

Question for me is why does an SRT hot shoe and engineer tell me that they have not experienced a loss of power at either the drag strip or on the road course or on the dyno. He tells me they did 100 runs down the strip and never noticed a loss of power. He tells me that the second run on the dyno was stronger than the first. Could there be a malfunction of some kind in the cars that are having this problem? Could there be a bad batch of IAT or other sensors that made their way into some production cars? Given the extensive on track testing SRT does I think this might be more likely. If they noticed this problem they would have fixed it for sure.

[FLATOUT]

Marc,

We don't have a problem with the Viper not being the absolute fastest thing down the quarter mile. We have a problem with them not working properly in the most basic of performance tests. If the car can't function properly from a dead stop why in the world would I want to own it? Not trying to be rude, but getting a bone stock car down the drag strip at the advertised power is as fundemental a performance measurement as it gets.

SRT has done a lot of screwy things with the ECU's on the cars since the Gen 4 came out, and I can tell you it has affected us on the road coarse as well. My car was going into limp mode for absolutely no reason at the top of each straight at MSR. I would have to bring it in to the pits reset everything and go back out and short shift those sections of the track until I could figure out what was causing it.

Eventually got it worked out at Tomball and all is well, but these things should not have issues like this, period.

It turns me off to the platform and makes me look elsewhere at slower cars that I can easily mod to make them more capable than a stock Viper.

[PaulB]

I think another point noteworthy of making is that if SRT did not intend on the V to spend some time at the drag strip or dig racing on the street, why would they go to the trouble of engineering and deploying Launch Control (such as it is) in these cars? And Mark, I laughed at your comment about AWD. I actively campaigned 2 full-on drag cars over a ten year period. There were no AWD full-on drag cars out there. Even with street classes there were only a few. I guess this is all just hyperbole anyway since until we hear something from SRT all the speculation in the world doesn't amount to a hill of beans.

[Garron]

Why would you idle a car for 25 min, heat soak it and then ¼ race it? I have another vehicle that is purposely built for drag racing, I cannot even imagine how bad my time would be if I did this.

Under these conditions any car would suffer poor times and a high intake temperature

[Voice of Reason]

Why would you idle a car for 25 min, heat soak it and then ¼ race it? I have another vehicle that is purposely built for drag racing, I cannot even imagine how bad my time would be if I did this.

Under these conditions any car would suffer poor times and a high intake temperature

Right now sitting at a stoplight on a warm summer day pushes IATs over 90 resulting in reduced power. We aren't talking about extended 25 min idle sessions here, it's a more common occurance.

[Jack B]

It does not take but a couple of minutes at idle then a shut down for the temp to climb.



Why would you idle a car for 25 min, heat soak it and then ¼ race it? I have another vehicle that is purposely built for drag racing, I cannot even imagine hwwwow bad my time would be if I did this.

Under these conditions any car would suffer poor times and a high intake temperature

[ViperGeorge]

Question for me is why does an SRT hot shoe and engineer tell me that they have not experienced a loss of power at either the drag strip or on the road course or on the dyno. He tells me they did 100 runs down the strip and never noticed a loss of power. He tells me that the second run on the dyno was stronger than the first. Could there be a malfunction of some kind in the cars that are having this problem? Could there be a bad batch of IAT or other sensors that made their way into some production cars? Given the extensive on track testing SRT does I think this might be more likely. If they noticed this problem they would have fixed it for sure.

Folks did anyone read my post? SRT DID test the car at the drag strip and on the dyno as well as on road courses. They DID NOT experience these problems. WHY? Could your car have a bad sensor or two? Some other problem maybe?

[VENOM V]

Folks did anyone ready my post? SRT DID test the car at the drag strip and on the dyno as well as on road courses. They DID NOT experience these problems. WHY? Could your car have a bad sensor or two? Some other problem maybe?

I agree, there must be some other issue at hand, or more to the story. A bad sensor or two, or perhaps hot air is getting into the intake from underhood, rather than cool air from outside. It'd be nice if SRT could participate in this discussion, as there have now been 189 posts and everyone has a theory. Could you ask the SRT engineer if someone could come on the forum? I know they're busy, but it wouldn't hurt to ask.

[ViperSmith]

Ralphs car dynos fine all day long and he does fine at the drag strip. I'd venture to guess he isn't towing the car to the drag strip when he goes.

There is something going on, and SRT needs to get to the bottom of it.

[pdv25]

Folks did anyone read my post? SRT DID test the car at the drag strip and on the dyno as well as on road courses. They DID NOT experience these problems. WHY? Could your car have a bad sensor or two? Some other problem maybe?

Good point. This issue has had me always looking at my IAT before each race. I can say I've not seen a difference when I raced the car back to back. Each race resulted in almost the same outcome. I'm no expert, just sharing what I noticed. Last race was a GTR (which are very consistent) 3 times in a row with the same outcome.

[Dman]

Ralphs car dynos fine all day long and he does fine at the drag strip. I'd venture to guess he isn't towing the car to the drag strip when he goes.

There is something going on, and SRT needs to get to the bottom of it.


This is it. THere's something happeing they're not seeing so what's out of kilter?? Once we know this, this all goes away with a simple fix, I'm sure, but not knowing is a REAL problem.

[99RT10]

Folks did anyone read my post? SRT DID test the car at the drag strip and on the dyno as well as on road courses. They DID NOT experience these problems. WHY? Could your car have a bad sensor or two? Some other problem maybe?

I think this is the car:

http://www.youtube.com/watch?v=iuhMUQwSvpY

[PaulB]

Folks did anyone read my post? SRT DID test the car at the drag strip and on the dyno as well as on road courses. They DID NOT experience these problems. WHY? Could your car have a bad sensor or two? Some other problem maybe?

LOL Yeah, I read your post. If this were one or two V's that were experiencing this, then I'd maybe think there was only a problem with one or two V's. Everyone I have talked to who has looked at this has seen the same thing so that leads me to believe that it is systematic and on a wholesale basis. Maybe the car they tested was not a production car? I don't know the answer to that but this is more than just one or two cars...

[PaulB]

Why would you idle a car for 25 min, heat soak it and then ¼ race it? I have another vehicle that is purposely built for drag racing, I cannot even imagine how bad my time would be if I did this.

Under these conditions any car would suffer poor times and a high intake temperature

I have had two cars that I drag raced too... When we pitted we ran the electric water pump and fan and depending on time between rounds sometimes would still be warm when we would head to the staging lanes and would push the car in the staging lanes until it was our turn for the burnout box. Yesterday was 73 degrees here (29 today, Texas weather lol).. anyway, when I parked my V in the parking garage it was seeing 120 degree IAT. One hour later when I came down to take it to my granddaughters school it was seeing 98 degree IAT when I got on the street. That's a 25 degree delta from outside temperature after an hour in a shaded garage. That sure doesn't seem right to me...

[Nine Ball]

Why would you idle a car for 25 min, heat soak it and then ¼ race it? I have another vehicle that is purposely built for drag racing, I cannot even imagine how bad my time would be if I did this.

Under these conditions any car would suffer poor times and a high intake temperature

Agreed. But, nobody does that. The IAT readings after a highway drive, followed by a simple 5 minute shut-down, result in start-up IAT's reading 120+ most of the time. Even if it is 65F outside. In the staging lanes, you tend to do a lot of start-stops to move your car up the line. I'm not pushing my car, as I'm not trying to set a record in it.

Sorry Mark, I disagree about the Viper only being meant for the roadcourse, and not good for drag racing. These cars should run solid 10s at 129-130 mph if they are seeing full power at the strip. That works out to being a pretty damn good drag car. We could be barking up the wrong tree, it might not be IAT at all. It could still be TCS/ABS/ESC crap, since this is the first year the Viper got two of those added. When I take off at the track, and have zero tire spin, with ESC/TCS off, it still feels like the throttle pedal is disconnected from the engine and resists more throttle. It feels very much like TCS limiting acceleration.

[99RT10]

Absolutely not designed for the 1/4, BUT neither is any other car specifically. Yes they put launch control on, but only to assist the beginners so they don't kill themselves running the car into a concrete bunker. Nannies can be bad too. Example:

http://www.youtube.com/watch?v=kzlg3oQMze4

[Back In Black]

I understand the need to protect the engine and to get the car out of it's warranty period before the engine fails but I think they've over engineered the ECU in that area. When the car goes into limp home mode because I removed the hood rain deflector, that's going overboard in my opinion.

I think this IAT issue is a case of the ECU being "overprotective".

There are '14 Vettes running 9's already. Wake up SRT!

[Coloviper]

Nine Ball, if you are experiencing where the car feels like it is artificially holding back like that. In the staging lane, turn the steering wheel all the way to the right and then back, while keeping it revved, them drop the clutch and go. I experienced this in the 07' SRT8 Jeep I had. For some reason, they program these newer vehicles to have more power for merging into traffic on a right hand turn. My Cayenne Turbo S is the exact same way. It is like it pulls up a completely different table map. It is very noticeable. I don't have a new GEN V but experienced it on many new vehicles out. Might help?

[99RT10]

Nine Ball, if you are experiencing where the car feels like it is artificially holding back like that. In the staging lane, turn the steering wheel all the way to the right and then back, while keeping it revved, them drop the clutch and go. I experienced this in the 07' SRT8 Jeep I had. For some reason, they program these newer vehicles to have more power for merging into traffic on a right hand turn. My Cayenne Turbo S is the exact same way. It is like it pulls up a completely different table map. It is very noticeable. I don't have a new GEN V but experienced it on many new vehicles out. Might help?

That is weird. I would love to know if that works. So should he do the burnout with the wheel locked to the right?

[Nine Ball]

Nine Ball, if you are experiencing where the car feels like it is artificially holding back like that. In the staging lane, turn the steering wheel all the way to the right and then back, while keeping it revved, them drop the clutch and go. I experienced this in the 07' SRT8 Jeep I had. For some reason, they program these newer vehicles to have more power for merging into traffic on a right hand turn. My Cayenne Turbo S is the exact same way. It is like it pulls up a completely different table map. It is very noticeable. I don't have a new GEN V but experienced it on many new vehicles out. Might help?

That would be pretty weird! I'll give anything a try at this moment, though. LOL

[Nine Ball]

That is weird. I would love to know if that works. So should he do the burnout with the wheel locked to the right?

You never want to do a burnout with the wheel turned. If the tires suddenly grab traction, you drive right into the wall. Here is a vid showing this happen. I was actually in the other dark gray Z06 waiting at the starting line for him...


http://www.youtube.com/watch?v=LyB4lejOtgA


http://www.youtube.com/watch?v=-oiWd0XpbSE

[chris955]

I bet you were glad that guardrail was there?

[Coloviper]

Always point the wheels straight forward when you take off, guess I just assumed people would. I know it is a weird little trick but it seems to work, at least by the seat of the pants feel. I have no hard numbers to prove however it definitely feels much more responsive, like it is chipped when it starts to take off. It has to be a turn all the way to the knuckle and then back with the revs holding up there.

[PaulB]

Do you have to have one eye closed and head tilted the opposite direction? :D Whatever works, I say!

[FLATOUT]

Do you have to have one eye closed and head tilted the opposite direction? :D Whatever works, I say!

Seriously lmao, what a circus.

[ViperSmith]

Blame the programmers :)

[Garron]

Always point the wheels straight forward when you take off, guess I just assumed people would. I know it is a weird little trick but it seems to work, at least by the seat of the pants feel. I have no hard numbers to prove however it definitely feels much more responsive, like it is chipped when it starts to take off. It has to be a turn all the way to the knuckle and then back with the revs holding up there.


The only way this would even work is if the stability control is in fact not 100% off.

[ViperGeorge]

The guy in the silver Vet was an idiot. He must have felt like a real loser driving back from the starting line.

[Disturbed]

Simple fact is your basing your arguments on the assumption that the sensor is right. The fact is, you do not know what the actual temps are at the runners and thats whats really important. That is undisputable fact.

Another undisputable fact is that the ECU does not know temp, it only knows resistance. We make that resistance repesent whatever we want it to represent.

If you stop and think about what I'm telling you, you will get it.

And your piggy back controller is doing nothing more than fooling sensors to do want we want the system to do. That is what ALL piggy back systems do.

I ALOT about how system work. How many multi-million dollar systems have you developed, the answer is none. I have designed flight control system, autonomous robots, I've worked with nano-bots, Gama Knife, Ultrasound, X-ray. Most of the stuff I have developed and refined over the last 19 years requires non-disclosure statements so I can't even go into details.

But make no mistake, if you stop, I can help you.

I'll be calling you today Dan to hash this shit out because either you are going to work with me, or we will keep fighting and either way, I'm cool with that.

Keep in mind I have never bashed anything you've done (other than your prices and stupid attitude). Remember you were the one who bashed my CF parts woth

[ViperSmith]

No one cares what you are writing at this point because it isn't contributing to the thread.

[pastohio]

There seems to be some good car people on this site, I will ask a question....Could it be low octane fuel ?? GM cars if using lower octane actually lose horsepower in the ecm to adjust for weaker fuel, then you pull fuses for about 8 hours to relearn the ecm unit...and then only use premium fuel thereafter to acquire tha max horsepower, etc....my $.02 ( unable to rad all the 9 pages but never seemsed to see anything about fueling and is the gas cap on tight ??!!

[Voice of Reason]

There seems to be some good car people on this site, I will ask a question....Could it be low octane fuel ?? GM cars if using lower octane actually lose horsepower in the ecm to adjust for weaker fuel, then you pull fuses for about 8 hours to relearn the ecm unit...and then only use premium fuel thereafter to acquire tha max horsepower, etc....my $.02 ( unable to rad all the 9 pages but never seemsed to see anything about fueling and is the gas cap on tight ??!!

I don't think its low octane. I fill up with 93 at the same station all the time. The only exception to this was when I tried a couple tanks of 100 octane from a nearby station this summer and I saw no difference at all.

And we do not have gas caps. :)

[99RT10]

You never want to do a burnout with the wheel turned. If the tires suddenly grab traction, you drive right into the wall. Here is a vid showing this happen. I was actually in the other dark gray Z06 waiting at the starting line for him...


http://www.youtube.com/watch?v=LyB4lejOtgA


http://www.youtube.com/watch?v=-oiWd0XpbSE

LOL, I was there for that one. That sucked for the guy.

[Rocket]

C'mon disturbed - keep it civil!

[FLATOUT]

C'mon disturbed - keep it civil!

Seriously, he doesn't have to agree with you (Disturbed), let it go and attempt to fix it your own way lol. People have differences of opinion every day.

[City]

We've requested some self moderation here. Hoping I can go back to sleep.

[Viper Specialty]

There is a difference between making your opinion known, and trying to convince everyone else that I have no idea what I am talking about in the process of making your opinion known. I generally try to explain my position which I did multiple times in this thread, but then you decided to take it to a personal level, and rather than explain why you were right, you jumped right to character assassination.



Simple fact is your basing your arguments on the assumption that the sensor is right. The fact is, you do not know what the actual temps are at the runners and thats whats really important. That is undisputable fact.

So you missed the whole part of the thread where I posted that I have tested this exact same scenario with OTHER sensors of known calibration specifically to see if the condition remained common to both? Do you also not understand what the term "Calibration" means? It means I KNOW exactly what the sensor is actually "seeing" versus what it is in actuality. THEY MATCH. IT IS CORRECT. They match both in calibration, AND testing with an alternate sensor type of known calibration.



Another undisputable fact is that the ECU does not know temp, it only knows resistance. We make that resistance repesent whatever we want it to represent.

It is not reading resistance, it is reading voltage. You tell the ECU a particular voltage equals a particular temperature, and everything is based on that information. If you then CHANGE the voltage calibration [incorrectly] by editing the resistance of the sensor... YOU JUST CHANGED THE TEMPERATURE TO AN INCORRECT VALUE AT ALL TIMES!



And your piggy back controller is doing nothing more than fooling sensors to do want we want the system to do. That is what ALL piggy back systems do.

Who said anything about a Piggy Back? You have absolutely no idea what we are working on.



I ALOT about how system work. How many multi-million dollar systems have you developed, the answer is none. I have designed flight control system, autonomous robots, I've worked with nano-bots, Gama Knife, Ultrasound, X-ray. Most of the stuff I have developed and refined over the last 19 years requires non-disclosure statements so I can't even go into details.

Of course you cannot go into detail, because you actually have no idea what you are talking about. It is plain as day to someone who actually understands this stuff and does it every day.


Keep in mind I have never bashed anything you've done (other than your prices and stupid attitude). Remember you were the one who bashed my CF parts woth

Actually, YOU started this my friend. It was started on the other thread, on the other site... and spilled over here.


TO EVERYONE ELSE:

I apologize about this back and forth BS. It is obviously fueled by some behind the scenes drama and not factual back and forth, but I feel I need to reply to this drivel to both keep my point on these topics in tact, and also explain "why" this nonsense is occurring. I know how easy it is to get lost in a thread this long, and I am not one to just walk away from finger-pointing. I tried to keep this short.

[KRATEDISEASE]

I ALOT about how system work. How many multi-million dollar systems have you developed, the answer is none. I have designed flight control system, autonomous robots, I've worked with nano-bots, Gama Knife, Ultrasound, X-ray. Most of the stuff I have developed and refined over the last 19 years requires non-disclosure statements so I can't even go into details.


Very Sorry, but ALL of your credibility just washed down the toilet with this statement above..."non disclosure" ?? Yah right.

Look you are not a vendor, So you can freely discredit Viper Specialty while you say that you have "non disclosure" agreements so therefore your "product" stays hidden ??

Are you sure you are not really SRTviper from the VCA ?

you had some credibility until this last post. Viper Specialty posted his credentials. You have chosen NOT to post yours ,BUT want to continue this debate.

Until you post your credentials and they can be verified.....YOUR TALKING POINTS are worthless.

[City]

I've just cleaned up the personal insults between 2 participants in this thread (at least I think I did). Nonetheless, it's an extremely interesting discussion with much valuable information. I tried as best as I could to leave the appropriate info intact.

PLEASE keep the conversation civil. I very much don't want to discourage any of the posters here. Just PLEASE find a way to express yourselves without disparaging another.

[SilveRT8]

I've just cleaned up the personal insults between 2 participants in this thread (at least I think I did). Nonetheless, it's an extremely interesting discussion with much valuable information. I tried as best as I could to leave the appropriate info intact.

PLEASE keep the conversation civil. I very much don't want to discourage any of the posters here. Just PLEASE find a way to express yourselves without disparaging another.

Good job ! Keep it up !

[mnc2886]

Anything from SRT yet?

[docwviper]

Agreed. Is SRT addressing this? I really hope so before spring hits. Please!!!

[KRATEDISEASE]

Anything from SRT yet?


How about someone private message John Hennessey and ask him to read the post ?? I have seen him post here on the VOA before.

Possibly he has some feedback ???

[cashcorn]

Better be fixed before the VERT comes out! hehehe...

[JonB ~ PartsRack]

I can confirm that the link and brief content descriptor to this thread was sent to the 'appropriate' SRT persons back on 11/12when it was only 3 pages long.....

[ViperSmith]

I can confirm that the link and brief content descriptor to this thread was sent to the 'appropriate' SRT persons back when it was only 3 pages long.....

Exactly! Plenty of us reached out (eg: complained) to SRT. I hopefully they get it sorted shortly!

[PaulB]

Interesting note.... I had called SRT a couple of weeks ago regarding this problem and to their credit they responded with a call back today. I was told by an SRT rep that my question of the excessively high IAT and its effect on performance had been posed to an engineer. The response was not to worry because the new intake was designed to lower temps and also the variable valve timing would also compensate to keep engine performance high...

Hmmmm......

[Viperbob]

On my 2 hour drive to Sebring this past weekend...during a half hour stint at 75 MPH in 6th gear ( approx 2k rpm) my IAT stayed 96 degrees constant ...Outside Temp was 79 degrees...on the drive home the next day same thing.
As soon as I would slow down but still moving through town no stops it would climb in the 100's and up to 125 when stopped ..again out side was 79'
Just seems ridiculous to me that the air box and intake tubes are getting BLASTED by the hot radiator heated air ..

This is with the bottom drain plug in the airbox Plugged!! so it wasn't sucking hot radiator air or getting hot air pushed up there. Additionally , I rerouted the crankcase vent tubes away from the air box ( plugged the hole) and intake plenum too so no hot air/gases were a factor from that....( I know the plenum isn't sensed by the IAT bit I don't want that nasty crankcase fumes in my intake)

I am going to put some heat shielding under the air box and around the intake tubes. Additionally, at some point I am going to come up with a deflector shield that sits under the air box and intake tubes so the hot radiator air is directed away as much as possible..

Ironically if you look at the C7 Vette ..they brilliantly direct the radiator air up directly through the hood in a sealed fashion and re-routed the airbox to the front side corner for true cold air intake unaffected by the radiator.. which is new for the vette that I remember the past few gens

Anyway, thought I would share my info so far

141214131414

[FLATOUT]

Bob, thought about just adding a catch can so you can get rid of that stuff?

[Viperbob]

Bob, thought about just adding a catch can so you can get rid of that stuff?

I am well aware of the catch can. However it has never been a problem for me ( 260 mile trip with spirited driving on and off the track not a drop of oil or even residue on the breathers...
Wasn't an issue on my Gen IV either with the same set-up...My view and my past two vipers have proved..unless your putting a ton of miles on your car and or constantly holding high RPMs for a long time....the catch can isnt needed..for my occasional usage....I open my hood after every drive ..and have monitored this set-up for years ..and no issues so far.

[F2V]

The new forum "SRT Headquarters/Factory" (coming soon), looks mighty interesting :car-smiley-003:

[Mamba52]

On my 2 hour drive to Sebring this past weekend...during a half hour stint at 75 MPH in 6th gear ( approx 2k rpm) my IAT stayed 96 degrees constant ...Outside Temp was 79 degrees...on the drive home the next day same thing.
As soon as I would slow down but still moving through town no stops it would climb in the 100's and up to 125 when stopped ..again out side was 79'
Just seems ridiculous to me that the air box and intake tubes are getting BLASTED by the hot radiator heated air ..

This is with the bottom drain plug in the airbox Plugged!! so it wasn't sucking hot radiator air or getting hot air pushed up there. Additionally , I rerouted the crankcase vent tubes away from the air box ( plugged the hole) and intake plenum too so no hot air/gases were a factor from that....( I know the plenum isn't sensed by the IAT bit I don't want that nasty crankcase fumes in my intake)

I am going to put some heat shielding under the air box and around the intake tubes. Additionally, at some point I am going to come up with a deflector shield that sits under the air box and intake tubes so the hot radiator air is directed away as much as possible..

Ironically if you look at the C7 Vette ..they brilliantly direct the radiator air up directly through the hood in a sealed fashion and re-routed the airbox to the front side corner for true cold air intake unaffected by the radiator.. which is new for the vette that I remember the past few gens

Anyway, thought I would share my info so far

141214131414

Here is a pic of the C7. The test unit kept intake air temps at ambient +5F and it is not fully sealed.

[FLATOUT]

http://i111.photobucket.com/albums/n133/ZOSICK/image_zpse69801f4.jpg (http://s111.photobucket.com/user/ZOSICK/media/image_zpse69801f4.jpg.html)

Going to give this a shot. I wrapped entire underside also. We'll put it on Nineballs car and see how much it affects the temps.

[Space Truckin]

What is the product?

[FLATOUT]

DEI gold heat reflective tape. Pricey but good. I use it on header installs.

[V10LEE]

http://i111.photobucket.com/albums/n133/ZOSICK/image_zpse69801f4.jpg (http://s111.photobucket.com/user/ZOSICK/media/image_zpse69801f4.jpg.html)

Going to give this a shot. I wrapped entire underside also. We'll put it on Nineballs car and see how much it affects the temps.

Andy that look's good. Did you buy this stuff on Amazon?
http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=DEI+gold+heat+reflective+tape

[ViperSmith]

$30 to cover 30sqft ain't bad

[FLATOUT]

That's the stuff, I got the bigger roll so I could do the underside also.

BTW ignore the toys in the background I have a 9 month old little girl lol.

http://i111.photobucket.com/albums/n133/ZOSICK/image_zpsb021dfb9.jpg (http://s111.photobucket.com/user/ZOSICK/media/image_zpsb021dfb9.jpg.html)



Andy that look's good. Did you buy this stuff on Amazon?
http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=DEI+gold+heat+reflective+tape

[ViperSmith]

Has the gen V airbox given you any performance improvement in your IV?

[Jack B]

Keep in mind heat is transferred via radiation, conduction and convection. The gold tape solves the heat transfer from radiation. A similar product with thermal insulation under the foil might work better, it would reduce the heat transfer from convection. The gold foil does have a good look/


QUOTE=V10LEE;11329]Andy that look's good. Did you buy this stuff on Amazon?
http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=DEI+gold+heat+reflective+tape[/QUOTE]

[FLATOUT]

Has the gen V airbox given you any performance improvement in your IV?

Yes, peak numbers went up 20rwhp and 32ftlbs, but I gained 30rwhp from 4500 to 5800 rpm. And that was then Gen V intake manifold, that's a stock gen IV air box (same as the gen V).

[FLATOUT]

Thanks Jack, I'll keep that in mind when we put it on Nineballs car.



Keep in mind heat is transferred via radiation, conduction and convection. The gold tape solves the heat transfer from radiation. A similar product with thermal insulation under the foil might work better, it would reduce the heat transfer from convection. The gold foil does have a good look/


QUOTE=V10LEE;11329]Andy that look's good. Did you buy this stuff on Amazon?
http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=DEI+gold+heat+reflective+tape[/QUOTE]

[Jack B]

I just bought a roll of the product that has the aluminum on the top side and a thin piece of insulation on the under side. It is also a DEI product, it came from Summit

.




Thanks Jack, I'll keep that in mind when we put it on Nineballs car.


[/QUOTE]

[ViperSmith]

Jack, this?

http://www.designengineering.com/category/catalog/design-engineering-inc/heat-sound-barrier/heat-screen

[FLATOUT]

Excellent. It took me a few hours to apply because I didn't want it to look ghetto. Easy project.


I just bought a roll of the product that has the aluminum on the top side and a thin piece of insulation on the under side. It is also a DEI product, it came from Summit

.


[/QUOTE]

[Viperbob]

What about covering the sensor housings also?

[Garron]

I just bought a roll of the product that has the aluminum on the top side and a thin piece of insulation on the under side. It is also a DEI product, it came from Summit

.


[/QUOTE]

That's the stuff we put on the air cleaner housing for the Competition coupe our race team runs. Gen 3-4 and 5 the Rad is pointed right at the air cleaner, this is not a new quirky problem. It would be nice to be able to direct the air away from the air cleaner housing a bit.

Are all the Gen 5's missing the rubber water drain on the bottom of the air cleaner housing, Gen 4's had it on the same air cleaner housing, it looks like they deleted it for the Gen 5.

[Steve M]

Curious to see if the foil helps...the gold stuff does look really nice.

[Jack B]

This is the product:


DEI Floor and Tunnel Shields 050503

It is a radiant barrier, plus, insulation. There are probably several similar products on the market. IMHO you want more than a radiant barrier, this product is 3/16' thick and also has an adhesive backing. The down side is that it will not look as good as a radiant barrier tape-only product.

Like any insulation you do not want to compress the material during the install.




Jack, this?

http://www.designengineering.com/category/catalog/design-engineering-inc/heat-sound-barrier/heat-screen

[FLATOUT]

Well the most important part is the underside which no one will really see. If anyone is concerned about the look they can always use the product jack is using on the bottom and the tape I used on the topside.