ACR Lift Throttle and car keeps accelerating

[CarbonDan]

Anyone else experience this and have a solution?
When doing a full throttle run up to 5-6k RPM and then lifting off the throttle, it seems like the car doesn't respond to the throttle being lifted for a good 2 seconds - it acts as if the throttle is still roughly halfway open.
Really unsettling feeling.

2017 ACR-E

[TKO MOTORSPORTS TEAM]

Sounds like normal factory viper DBW throttle CarbonDan. Your correct "unsettling" to say the least. Easy fix our max throttle kit. tkomotorsports.com Easy to install, adjustable fixes all the lag in DBW viper throttle. If you run your viper at the track alot our pro max throttle kit is the way togo. If you have fun with your viper street and occasional track then go with our quick install max throttle kit save a couple bucks. Alot of people on the VOA are customers who have installed our max throttle kits. Sure you will get some good info from them on this thread about our max throttle kits.

[Arizona Vipers]

Sounds like you need a throttle relearn, this same thing happened to me once. The dealer had to do a throttle relearn and it fixed it.

[Steve M]

The blades should be closing immediately after you let off of the gas...this has nothing to do with throttle response, and if it is happening as you say, is a major safety concern. Something is not right with the programming...there are multiple checks, balances, and redundancies within any DBW system to prevent what you are describing.

Assuming you've done the basics like making sure the gas pedal isn't somehow getting stuck, a trip to the dealer would be the next thing to do.

[TKO MOTORSPORTS TEAM]

Anyone else experience this and have a solution?
When doing a full throttle run up to 5-6k RPM and then lifting off the throttle, it seems like the car doesn't respond to the throttle being lifted for a good 2 seconds - it acts as if the throttle is still roughly halfway open.
Really unsettling feeling.

2017 ACR-E

You shouldn't need a dealer for a relearn. Most ECU/PCM work very similar nowadays for relearn.
Simple battery disconnect will reset all the engine adaptives in the PCM/ECU; disconnect battery, wait 5 min, reconnect battery; adaptives are gone. The capacitors in PCM/ECU will loose voltage after about 10 seconds or so but leave battery disconnected for 5 min just to be safe. .

After a battery disconnect reconnect and cycle the ignition from off to run about 7-10 times without starting. This will relearn your pedal adaptive.

Throttle learn, cycle the key from off to run (don't start the engine), and wait about 5 seconds. As the fuel pump runs, throttle will also perform a spring test. The throttle blade will perform a full open sweep to learn a number of values for throttle position.

It still sounds like standard viper lazy throttle problem but it wont hurt anything to do a relearn.

[SRT BILL]

You shouldn't need a dealer for a relearn. Most ECU/PCM work very similar nowadays for relearn.
Simple battery disconnect will reset all the engine adaptives in the PCM/ECU; disconnect battery, wait 5 min, reconnect battery; adaptives are gone. The capacitors in PCM/ECU will loose voltage after about 10 seconds or so but leave battery disconnected for 5 min just to be safe. .

After a battery disconnect reconnect and cycle the ignition from off to run about 7-10 times without starting. This will relearn your pedal adaptive.

Throttle learn, cycle the key from off to run (don't start the engine), and wait about 5 seconds. As the fuel pump runs, throttle will also perform a spring test. The throttle blade will perform a full open sweep to learn a number of values for throttle position.

It still sounds like standard viper lazy throttle problem but it wont hurt anything to do a relearn.

Marty, do you know if the throttle relearn you described above will work for the arrow controller? I've been wanting to change out my stock one for the off road Arrow controller for some time but this throttle relearn thing seems to get in the way.
Thanks for any help.

Bill

[TKO MOTORSPORTS TEAM]

Marty, do you know if the throttle relearn you described above will work for the arrow controller? I've been wanting to change out my stock one for the off road Arrow controller for some time but this throttle relearn thing seems to get in the way.
Thanks for any help.

Bill

It should but better ask Scott from arrow/prefix first Bill just to be safe. He might also have some better tricks if your switching ECU

[Arizona Vipers]

Marty, do you know if the throttle relearn you described above will work for the arrow controller? I've been wanting to change out my stock one for the off road Arrow controller for some time but this throttle relearn thing seems to get in the way.
Thanks for any help.

Bill

Trust me it won't. Needs the fancy Weitech dealer tool. If you do indeed a throttle relearn and that's what's causing this problem you have to have the dealer do it. Although was talking to Scot at Prefix lately about this and he said they were working on something that would allow people to do it at home with HP Tuners I think.

[TKO MOTORSPORTS TEAM]

Usually a basic throttle relearn is no problem standard procedure. Your not tuning your just doing basic restart. Any time replacing the battery or disconnect the battery for more then 10-20 seconds the factory ECU will go through basic restart, relearn and adaptives.

do you have the factory ECU in your viper Bill?
Did you do some work on your viper and then you had the throttle problem? Or did the throttle just start out of the blue one day having this problem?
any DTC ? check engine light, stored codes if you have a way to read them??

[SRT BILL]

Usually a basic throttle relearn is no problem standard procedure. Your not tuning your just doing basic restart. Any time replacing the battery or disconnect the battery for more then 10-20 seconds the factory ECU will go through basic restart, relearn and adaptives.

do you have the factory ECU in your viper Bill?
Did you do some work on your viper and then you had the throttle problem? Or did the throttle just start out of the blue one day having this problem?
any DTC ? check engine light, stored codes if you have a way to read them??

Yes,I have the original factory ECU that has never been removed. I also have a new Arrow ECU thats programmed to my vin# but never installed. I've been waiting for warranty reasons. I have already installed your Max Throttle but would like to take another step forward and install the Arrow ECU. The re-learn thing is the problem.

[Steve M]

Trust me it won't. Needs the fancy Weitech dealer tool. If you do indeed a throttle relearn and that's what's causing this problem you have to have the dealer do it. Although was talking to Scot at Prefix lately about this and he said they were working on something that would allow people to do it at home with HP Tuners I think.

This is my understanding as well.

To clarify some things:

1. HPTuners and the Arrow PCM are two completely different animals, but both may require the same throttle relearn procedure in order to function properly.
2. There have been folks that have gotten both HPTuners and the Arrow PCM to work without doing a throttle relearn, but it is a craps shoot. Sometimes the tolerances line up in your favor, and sometimes they don't. You can try installing the Arrow PCM (assuming it is already programmed with your VIN and mileage), and see if it works or not. If it doesn't, you'll know it pretty quick - it'll go into limp mode. Same with HPT.
3. The throttle relearn functionality is built in to HPTuners, but it requires you to write the HPT custom operating system first to work. You have to be able to connect to the PCM to communicate with it through the HPT scanner, and you cannot communicate with the PCM unless the custom OS is in place first. Because of this, I don't think you'll ever be able to get HPT to do a throttle relearn on an Arrow PCM, unless they change something. You could potentially program a handheld controller of some sort to perform this function though, like a wiTECH lite or something.

I think some folks are getting confused in this thread on the terminology. I'm not sure what exactly the PCM measures during the throttle relearn, but it is definitely more than just resetting adaptives with the Gen 4/5 Vipers. When I've commanded it on mine (with HPT), it makes quite the racket...you can hear the throttle blades clicking and clacking for about 10 seconds while they get their bearings, and it is LOUD. If you aren't hearing that, you aren't doing a throttle relearn. It also requires you to put the gas pedal to the floor (and verify), and then let off the gas pedal (and verify) - that tells the PCM the where the limits of the gas pedal travel are. Again, if you aren't doing that, you aren't doing a throttle relearn. All of those things are required for the DBW system to be calibrated properly.

Bottom line: outside of folks using HPTuners, you need a wiTECH to do the actual throttle relearn procedure. It is usually a one-time only thing, unless you do something that alters the throttle bodies (like when I switched from the plastic to metal throttle bodies on my Gen 4). This gives the PCM a baseline as to the limits of the throttle blade travel, and also the gas pedal travel. This may help the OP, but the initial throttle relearn for the Arrow PCM is a separate issue that is derailing this thread.

[SRT BILL]

It was not my intention to derail OP's thread but do see your point. Thank you for the great info which I beleive will help everyone.

[Steve M]

It was not my intention to derail OP's thread but do see your point. Thank you for the great info which I beleive will help everyone.

Not entirely your fault...I was more concerned when I read this:

Usually a basic throttle relearn is no problem standard procedure. Your not tuning your just doing basic restart. Any time replacing the battery or disconnect the battery for more then 10-20 seconds the factory ECU will go through basic restart, relearn and adaptives.

do you have the factory ECU in your viper Bill?
Did you do some work on your viper and then you had the throttle problem? Or did the throttle just start out of the blue one day having this problem?
any DTC ? check engine light, stored codes if you have a way to read them??

Based on my read of TKO's post above, it appears that TKO is mistaking you for the OP (CarbonDan). You both have very different problems, but the solution may end up being the same (the wiTECH throttle relearn procedure).

What CarbonDan is describing to me sounds like a runaway throttle condition. The throttle blades should only be following the gas pedal inputs; e.g. if you push the gas, they should open a certain amount, and if you let off, they should close. The PCM will keep them cracked to maintain idle, but that's about it. That's why I recommend the following actions to rule out any problems:

1. Make sure the gas pedal is moving freely - it should not stick at any point in its travel
2. Make sure there's nothing that the gas pedal is getting caught on - if it were me, I'd remove the floor mat entirely and try driving it again to rule out that possibility.
3. If #1 & #2 check out, then pursue the throttle relearn procedure. Again, this isn't a simple disconnect the battery procedure that resets any learning that the PCM has done. The correct procedure allows the PCM to learn the throttle body voltages throughout their travel; same thing for the gas pedal. That information serves as its baseline, and allows it to know what is acceptable with the parts that are installed on each individual car. Tolerances vary among all the electronics used on any given car, and the DBW system works within pretty tight tolerances for safety - there's little margin for error. The default when something is out of line is for the PCM to clamp the throttle blades down first and ask questions later.

Over the years, I've come to appreciate that the Viper is a unique animal, and it is mostly due to the engine controller. What works as a "standard procedure" for one brand of vehicle may not work for this one. There are also no guarantees that something proven to work for another Mopar vehicle (e.g. Challenger, Charger, etc.) will work for the Viper. The engine controller is unique to this platform; nothing else in the FCA lineup uses it.

[Arizona Vipers]

Not entirely your fault...I was more concerned when I read this:



Based on my read of the post above, it appears that TKO is mistaking you for the OP (CarbonDan). You both have very different problems, but the solution may end up being the same (the wiTECH throttle relearn procedure).

What CarbonDan is describing to me sounds like a runaway throttle condition. The throttle blades should only be following the gas pedal inputs; e.g. if you push the gas, they should open a certain amount, and if you let off, they should close. The PCM will keep them cracked to maintain idle, but that's about it. That's why I recommend the following actions to rule out any problems:

1. Make sure the gas pedal is moving freely - it should not stick at any point in its travel
2. Make sure there's nothing that the gas pedal is getting caught on - if it were me, I'd remove the floor mat entirely and try driving it again to rule out that possibility.
3. If #1 & #2 check out, then pursue the throttle relearn procedure. Again, this isn't a simple disconnect the battery procedure that resets any learning that the PCM has done. The correct procedure allows the PCM to learn the throttle body voltages throughout their travel; same thing for the gas pedal. That information serves as its baseline, and allows it to know what is acceptable with the parts that are installed on each individual car. Tolerances vary among all the electronics used on any given car, and the DBW system works within pretty tight tolerances for safety - there's little margin for error. The default when something is out of line is for the PCM to clamp the throttle blades down first and ask questions later.

Over the years, I've come to appreciate that the Viper is a unique animal, and it is mostly due to the engine controller. What works as a "standard procedure" for one brand of vehicle may not work for this one. There are also no guarantees that something that works for another Mopar vehicle (e.g. Challenger, Charger, etc.) will work for the Viper. The engine controller is unique to this platform; nothing else in the FCA lineup uses it.

When I need the throttle relearn this was the EXACT symptoms. I had just got a new motor back from Prefix, took it to the track. Noticed right away every shift the car would take a huge jump in RPM's once the clutch went in and throttle went off. I knew right away it need a relearn. Took it to Eddie Martin and the relearn fixed it.

[CarbonDan]

Thanks gents, will be having the dealer hook it up for a relearn. Will report back.
Definitely nothing getting caught in there, battery reset, etc. Done all the straightforward troubleshooting already. Will let you know the final fix

[Jack B]

Absolutely not normal.This happened on my car and it was the floor mat. When I slowed the car and pulled over, the floor mat had separated from the pedal, therefore, I had no idea of the cause. I eventually duplicated the problem doing what-ifs with the engine off.

[ViperGeorge]

CarbonDan, you don't say if your car is modified or not. Do you have headers? If so, headers can melt wires inside the main harness and cause strange things to happen. Outside of harness may look perfectly normal but inside can be melted. None the less, a throttle relearn is likely the cause if your car is stock.

[CarbonDan]

Nope totally stock, had 650 miles on it when I bought it 2-3 months ago and problem existed since then. The pedal feels really loose and floppy though, which I took notice of yesterday. I'll have to take a video and upload it to show just how much play there is in the gas pedal.

[ViperGeorge]

I suppose a bad throttle position sensor could also cause your problem. Unfortunately the sensor can only be had by changing the whole pedal assembly.