is this idle normal

[ayousef]

Well, my car feels like it has a baby camshaft in it. Idles rough, sounds nice and it shakes slightly but aside from being "cool", is this how a Viper is supposed to idle? My car has the Arrow controller, and Nthmoto triple carbon clutch (lighter flywheel), and underdrive pulley, headers +exhaust, filter. Lots of clutch chatter as well at idle with the clutch engaged (pedal out).



Sorry for the portrait video, wasnt thinking when I recorded it.

[SRT_BluByU]

tough to quantify normal when you have all those mods. the rpm does look like its hunting quite a bit

[ayousef]

Well the mod that makes the most sense as to cause such a thing is the clutch, I cant see how anything else would do this but I made sure to mention everything. I would guess this idle speed is very low for a car with a lighter flywheel, but I am trying to make sure its not spark plug or camshaft VVT related.

Since were at it, heres a clear video of that clutch chatter.

[ViperGeorge]

I agree idle seems to be hunting around a bit much. I had this problem with my 09 ACR with ARH headers. Headers developed a leak at the collector. Was screwing up the O2 sensor readings. Fixed the leak and it fixed the idle. My Viper tech did a smoke test on the exhaust and found the leak. Dollars to donuts this is your problem.

[TrackAire]

Maybe the video is distorting the sound of the clutch but it doesn't sound anything like neutral clutch chatter (or better yet "rattle") to me.....almost sounds like it's knocking.

Again, maybe the video is distorting what I'm hearing. Let us know what you find out.

[Gen3CoupeTX]

Yes, the idle seems to be searching for its spot ... But it does sound pretty cool as you said! I've not had one search like that, even my current supercharged Gen 3 coupe. Good luck on the fix. I really couldn't hear the clutch chatter, but confident you can.

[cubeman]

I have that same issue, I throw a code if I idle excessively. Working with arrow/prefix on it now might be the vacuum line thingy. Arrow PCM, ARH Headers, Cats, Exhaust, Underpulley, K&N Filter now stock. I thought the filter was causing it so i swapped to stock, same issue. Temps low by you? This started for me around winter

[Steve M]

Does anyone else have clutch chatter with the Nth moto clutch? I'm getting ready to pull the trigger on one for my Gen 4, but that would drive me up the wall.

[Jack B]

Does anyone else have clutch chatter with the Nth moto clutch? I'm getting ready to pull the trigger on one for my Gen 4, but that would drive me up the wall.

Question for the OP,,what is meant by clutch chatter at idle. The Nth Moto will rattle a bit at idle in neutral due to design, but,chatter, it should not.

Steve:
When the Nth Moto is installed correctly they seem bullet prove and smooth. You will love it. I have tried several other brands and they do not seem better than the oem, the exception has been the Nth Moto.

The key with the Nth Moto is:
1. Lapping the spline.
2. Greasing the spline correctly.
3. Making sure the throwout bearing set back is correct.
4.Making sure the throwout bearing spacer is seated correctly.
5. Forcing the input shaft/trans into clutch. You want to make sure you are parallel and flat with the bell housing. It is more critical due to length of the internal splines.

The trans installation is compounded by some aftermarket headers, they do not allow the the engine to drop far to keep an unobstructed entry of the input shaft into the clutch. When the trans does not drop down enough the top of the trans hits underside of the trans tunnel.

If not done correctly anyone of the above can cause issues. When you see the design of all the parts you will wonder why all clutches are not done the same way.

[Steve M]

Question for the OP,,what is meant by clutch chatter at idle. The Nth Moto will rattle a bit at idle in neutral due to design, but,chatter, it should not.

Jack,

In your opinion, is the video posted above about normal, or does that seem like an excessive amount of rattling coming from the clutch? Just looking for some honest feedback before dropping $4k on a clutch.

[Dman]

I’ve had stock, stage 1 with Arrow controller, and now stage 2 with HC and solid cam. None of my setups across two gen5’s have had a hunting idle like that. What ‘filter’ did you do? We’ve seen some freaky behavior from filter changes here and there.

The clutch noise I have no exp with, mine have all been stock, but in general, that doesn’t sound right, as in normal chatter to me. But I haven’t heard an Nth Moto setup.

[ViperGeorge]

See my previous post. As I said I'll bet you dollars to donuts your problem is an exhaust leak upstream of one of the front O2 sensors. The leak causes changes in the O2 sensor readings causing the PCM to constantly adjust fuel causing the idle to hunt. Listen to Jack re the clutch, he knows what he is talking about.

[cubeman]

See my previous post. As I said I'll bet you dollars to donuts your problem is an exhaust leak upstream of one of the front O2 sensors. The leak causes changes in the O2 sensor readings causing the PCM to constantly adjust fuel causing the idle to hunt. Listen to Jack re the clutch, he knows what he is talking about.

My car is going to CJ at Meadowlands Monday for a Diff fluid swap, while it's up there I'll ask to check for exhaust leaks.

[ayousef]

thanks for all the replies guys. I will be installing the stock ECU and trying to play with hptuners. At least I will be able to see if its an exhaust leak from o2 sensor log however I will also "try" to do a visual since thats a pretty hard task on our cars without removing the side sill (which is a pain in the back). I did open up the pipe that has the catalytic converter on it once to check if the cats were still alive, however I re-welded back that clamp after I put it back. My entire exhaust clamps are all welded so the exhaust shouldnt leak.

Now, I also know that cars with lighter flywheels or underdrive pulleys usually need higher RPM to remain smooth, and I can say that the idle was super smooth at 1000rpms when I first got the car, but I also remember that the last time I swapped the arrow PCM for the stock PCM, and since the stock pcm is still a "virgin" meaning it still idles at 1000rpms (which is kind of the stupidest thing ive seen on any car) and will keep on doing so for the next 700 miles then gradually drop down it wasnt as smooth as when I first got the car, idle still hunted.

the filter I have is the K&N replacement only, I cant see how this would cause any problem?

Also worth mentioning is that I once did a 2nd to 3rd pull and as soon as I clutched in, the engine died. The car is pretty hard to drive the way it is, requiring the throttle pedal to get moving, cant even think of de-clutching gradually, that simply does not work, revs drop down to say 400ish rpm's and have a very hard time pulling itself back up, assuming it does not stall before that.

I did also have this clutch on my Camaro, this exact same RPS unit, perhaps different flywheel weights and it wasnt easier to drive, but I dont remember it rattling like this, but then that car was louder to begin with.

Finally, perhaps I am not using the correct terminology as to wether this is a rattle or chatter but its super loud, and I get asked about it all the time, it sounds like something is broken (which I dont mind minus the weird looks I get from friends and other people). As soon as I clutch in the sound disappears. I will try to get another video of the car with the stock ECU.

For those who want to install the Nthmoto clutch, try it before you install it, its an expensive unit so better be informed, your results may be different? Or at least if you dont have enough power to make use of it then dont. The only reason I installed it is because its lighter. Ill get back with more info and a video.

[ayousef]

thanks for all the replies guys. I will be installing the stock ECU and trying to play with hptuners. At least I will be able to see if its an exhaust leak from o2 sensor log however I will also "try" to do a visual since thats a pretty hard task on our cars without removing the side sill (which is a pain in the back). I did open up the pipe that has the catalytic converter on it once to check if the cats were still alive, however I re-welded back that clamp after I put it back. My entire exhaust clamps are all welded so the exhaust shouldnt leak.

Now, I also know that cars with lighter flywheels or underdrive pulleys usually need higher RPM to remain smooth, and I can say that the idle was super smooth at 1000rpms when I first got the car, but I also remember that the last time I swapped the arrow PCM for the stock PCM, and since the stock pcm is still a "virgin" meaning it still idles at 1000rpms (which is kind of the stupidest thing ive seen on any car) and will keep on doing so for the next 700 miles then gradually drop down it wasnt as smooth as when I first got the car, idle still hunted.

the filter I have is the K&N replacement only, I cant see how this would cause any problem?

Also worth mentioning is that I once did a 2nd to 3rd pull and as soon as I clutched in, the engine died. The car is pretty hard to drive the way it is, requiring the throttle pedal to get moving, cant even think of de-clutching gradually, that simply does not work, revs drop down to say 400ish rpm's and have a very hard time pulling itself back up, assuming it does not stall before that.

I did also have this clutch on my Camaro, this exact same RPS unit, perhaps different flywheel weights and it wasnt easier to drive, but I dont remember it rattling like this, but then that car was louder to begin with.

Finally, perhaps I am not using the correct terminology as to wether this is a rattle or chatter but its super loud, and I get asked about it all the time, it sounds like something is broken (which I dont mind minus the weird looks I get from friends and other people). As soon as I clutch in the sound disappears. I will try to get another video of the car with the stock ECU.

For those who want to install the Nthmoto clutch, try it before you install it, its an expensive unit so better be informed, your results may be different? Or at least if you dont have enough power to make use of it then dont. The only reason I installed it is because its lighter. Ill get back with more info and a video.

[ayousef]

UPDATE: okay so I installed the factory ECU and hooked up HPTuners and tuned the crap out of the car, managed to get it to drive really good, but I cant for the life of me figure out why commanded AFR (or EQ ratio) in the tune does not match the log. I disabled everything that could effect this, but im still left with this big discrepancy.

Anyhow, as far as the idle, since this ECU is a virgin, idle is up to 1000rpms and is very smooth. Clutch rattle is also gone at higher rpms. So for those people interested in the clutch, better be ready to idle high. I also added idle timing to help pull the car from a stop all of which helped. The clutch is still hard to drive, so unless you need it dont upgrade. I wish they made one with a heavier flywheel, as long as the entire assembly does not weigh more than the stock clutch it should be fine.

So now back trying to figure out the HPTuners AFR problem.

[ViperGeorge]

UPDATE: okay so I installed the factory ECU and hooked up HPTuners and tuned the crap out of the car, managed to get it to drive really good, but I cant for the life of me figure out why commanded AFR (or EQ ratio) in the tune does not match the log. I disabled everything that could effect this, but im still left with this big discrepancy.

Anyhow, as far as the idle, since this ECU is a virgin, idle is up to 1000rpms and is very smooth. Clutch rattle is also gone at higher rpms. So for those people interested in the clutch, better be ready to idle high. I also added idle timing to help pull the car from a stop all of which helped. The clutch is still hard to drive, so unless you need it dont upgrade. I wish they made one with a heavier flywheel, as long as the entire assembly does not weigh more than the stock clutch it should be fine.

So now back trying to figure out the HPTuners AFR problem.

You didn't say which brand of headers you have. With the ARH headers a leak can develop where you bolt the pieces together at the collector. Bolting these pieces together is one of the harder things to do with the install. I don't know if Bellangers have the same issue. Jack can comment as he has done both. If a leak is upstream of the O2 sensor. The leak causes the PCM to constantly try to adjust A/F based on inaccurate data from the O2 sensor. A leak downstream of the front O2 will not cause this problem.

[Jack B]

You are correct they both can leak, but, for diff reasons. Belanger claims they do not need gaskets on the three flanges, IMHO, you need gaskets. Since the Belangers are usually light colored you may be able to see a flange leak from underheath.

As a note, starting with the HC cars the Arrow pcm does not use the O2 sensors.

You didn't say which brand of headers you have. With the ARH headers a leak can develop where you bolt the pieces together at the collector. Bolting these pieces together is one of the harder things to do with the install. I don't know if Bellangers have the same issue. Jack can comment as he has done both. If a leak is upstream of the O2 sensor. The leak causes the PCM to constantly try to adjust A/F based on inaccurate data from the O2 sensor. A leak downstream of the front O2 will not cause this problem.

[ViperSRT]

You are correct they both can leak, but, for diff reasons. Belanger claims they do not need gaskets on the three flanges, IMHO, you need gaskets. Since the Belangers are usually light colored you may be able to see a flange leak from underheath.

As a note, starting with the HC cars the Arrow pcm does not use the O2 sensors.

Really? No closed loop operation at all.

[Jack B]

Really? No closed loop operation at all.

On day one I saw trims were missing, so I contacted Winkles, he confirmed it was normal on HC cars.

[ayousef]

I wonder if there’s a problem with the install of the clutch. I remember reading a post from Andy where his Nth clutch had issues at first. After some adjustments it then worked just like stock. I don’t think I’ve read a single other post about people having issues with the Nth clutch. I hope you get it worked out!

Im guessing not alot of people have the nthmoto clutch but I could be mistaken. Also the clutch was installed by the guys at Viper Exchange before the car was shipped to me, so im guessing they have done the procedure but what do I know?

You didn't say which brand of headers you have. With the ARH headers a leak can develop where you bolt the pieces together at the collector. Bolting these pieces together is one of the harder things to do with the install. I don't know if Bellangers have the same issue. Jack can comment as he has done both. If a leak is upstream of the O2 sensor. The leak causes the PCM to constantly try to adjust A/F based on inaccurate data from the O2 sensor. A leak downstream of the front O2 will not cause this problem.

Im pretty sure its not a leak, my fuel trims are 100% perfect and very close to zero at all times. Also the car idles very smoothly once the idle was raised to 1000rpms. I am pretty sure it will idle smoothly even with slightly lower idle speed, but I have yet to find that out since the new ECU will only idle at 1000rpms for about 500miles. Once it drops I can find the lowest smooth idle spot.

[Steve M]

When is the commanded equivalence ratio not matching? WOT only? I can take a look at your logs and tune if you think it would help.

[ayousef]

When is the commanded equivalence ratio not matching? WOT only? I can take a look at your logs and tune if you think it would help.

yes, at cruising its 1.0 but it stops making sense at WOT. I can send you the log and tune.

I wonder if this is one of the stupid tricks in the ECU where it runs richer for the break-in miles, since this ECU has never been used. For example, the idle is 1000rpms despite it being commanded as 700rpms in the tune. If I raise the 700 to 800, then the idle goes from 1000 to 1100. I wonder if the same theory applies for the AFR discrepancy.

[Voice of Reason]

I wonder if there’s a problem with the install of the clutch. I remember reading a post from Andy where his Nth clutch had issues at first. After some adjustments it then worked just like stock. I don’t think I’ve read a single other post about people having issues with the Nth clutch. I hope you get it worked out!

[cashcorn]

My idle was hunting just as yours is after installing the underdrive pulley. I then installed the 1" shorter belt & now it's perfect..