Motor stalls at idle - Need Help

TorontoACR

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My 02 ACR is stalling at a dead stop at idle. I have to always rev it up to keep it from stalling. I notice though that it does not stall if i put it in neutral and then coast it to a stop. But once I reach a stop it again will stall out. I cleaned the air filter etc. Anybody know what is causing this as it is almost causing to make an accident

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britospeed

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Check you IAC valve. Front passenger side of the engine, it has a 4 pin connector
 

Steve-Indy

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Agree with IAC checkup...connector or the motor itself. Tom posted the rehab process...try a search.

Occasionally, a failing battery will cause this type of problem before it dies completely.
 

viper spray

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On my 97 GTS I replacedc the IAC with a new one from my dealer and put in a new battery and it cured the problem. On my car with the aftermarket sound system if the batt. is not fairly new and in great shape , the car will die at idle. Do those two things and I would bet that it fixes it. I cleaned my IAC several times with sensor safe TB cleaner and it fixed it for an hour or two. Good luck.
spray...........
 
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TorontoACR

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Hard to believe its the battery causing the problem as I can start the car without problem. How cam you tell if the battery is not up to par. How can I check to see if the IAC is having problems and needs replacing.
 

Tom F&L GoR

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The IAC valve can be easily removed and inspected. It is (oversimply described) a large pencil tip that enters a calibrated hole. The solenoid positions the tip to a depth in the hole to allow enough air to pass through to idle.

No fuel passes through this valve, only crankcase ventilation gases. Therefore the additives in gasoline cannot keep it clean. If you inspect it and there are deposits of any volume on the tip or in the hole, they need to be cleaned off. The tip should feel relatively free in motion and the stem should not feel sticky.

I have removed and cleaned these successfully, but be aware that if the engine senses the IAC has been disconnected (accidentally turn the key, or even install a new one) it will have to re-learn the idle position. This actually takes a few trips and in the meantime the symptoms are just as you describe - poor idling, stalling, but easy to start. Have you disconnected it or the battery recently?

Viper techs say that using the A/C speeds the relearning process (perhaps because the idle position is increased due to the engine load of the compressor.) Maybe try driving with the AC or defroster on and see what the symptoms are. Good luck.

An IAC valve is around $125, same is used on 1992-2004.
 
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TorontoACR

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Thanks for the great description. I will try to clean this over the weekend. Anybody have any detailed pictures on how to remove, clean and reinstall the IAC without having to pay for the subscription on Viper Club. Things are a bit tough right now

Appreciated

The IAC valve can be easily removed and inspected. It is (oversimply described) a large pencil tip that enters a calibrated hole. The solenoid positions the tip to a depth in the hole to allow enough air to pass through to idle.

No fuel passes through this valve, only crankcase ventilation gases. Therefore the additives in gasoline cannot keep it clean. If you inspect it and there are deposits of any volume on the tip or in the hole, they need to be cleaned off. The tip should feel relatively free in motion and the stem should not feel sticky.

I have removed and cleaned these successfully, but be aware that if the engine senses the IAC has been disconnected (accidentally turn the key, or even install a new one) it will have to re-learn the idle position. This actually takes a few trips and in the meantime the symptoms are just as you describe - poor idling, stalling, but easy to start. Have you disconnected it or the battery recently?

Viper techs say that using the A/C speeds the relearning process (perhaps because the idle position is increased due to the engine load of the compressor.) Maybe try driving with the AC or defroster on and see what the symptoms are. Good luck.

An IAC valve is around $125, same is used on 1992-2004.
 

Jack B

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Thanks for the great description. I will try to clean this over the weekend. Anybody have any detailed pictures on how to remove, clean and reinstall the IAC without having to pay for the subscription on Viper Club. Things are a bit tough right now

Appreciated

It is easy to pull off. As was stated, passenger side -front of intake. Remove the the hose, electrical connector and the bolts. You might want to pre-order the gasket, it is fragile and the first time it is removed it may fracture. I would clean the IAC with MAF cleaner.
 
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TorontoACR

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Thanks Jack. I took it out. Gasket broke as you said, cleaned it well. It was idling great for a short time. it had a nice and smooth idle when normally it is rough. But after i drove it on the highway and it heated up, it once again stalled at idle. It is a real pain as it stalls all the time at idle. Would you say I have no choice but to order a new IAC or is there something else that can fix this

It is easy to pull off. As was stated, passenger side -front of intake. Remove the the hose, electrical connector and the bolts. You might want to pre-order the gasket, it is fragile and the first time it is removed it may fracture. I would clean the IAC with MAF cleaner.
 

Dan Cragin

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Check your battery, if the voltage drops too low during start-up then the computer will not remember its idle position and will need to relearn it.
 

Dom426h

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I saw where you were looking the CamPS in the other thread.
I'd forget about that for now. I dont think it matches you symptoms. Id foccus on the IAC and TPS(throttle position sensor). Both very easy to replace and can temporarily swap with a fellow viper owner to see if fix befor spending the $$$.

Have you read this thread?
http://forums.viperclub.org/rt-10-gts-discussions/594036-car-dies-when-stopping.html
or this one
http://forums.viperclub.org/rt-10-gts-discussions/530188-annoying-idle-problem-solution.html
or this one
http://forums.viperclub.org/rt-10-gts-discussions/607406-need-code-help.html
or
http://forums.viperclub.org/rt-10-gts-discussions/608183-iac-motor-pintle-always-open.html


Have you reset your ECU?

Have you talked to the Wizard?
 
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TorontoACR

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Thanks, I will try a bit of WD40 as maybe the piston in the sensor is jammed. But I did spry a lot of cleaner which also has a bit of a lubricant. If that does not work, are their any viper owners in the Toronto region that will allow me to swap one just to try it out as the guys here have suggested. Thanks for the input

Squirt a little WD40 in the IAC after you clean it.
 
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TorontoACR

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I took the advise and sprayed on a bit of wd-40 or something similar. It worked great. As it heated up it did get a bit rougher, but it has not shut down. It is working. I think it is about 90% back to normal. I think I will need to install a new IAC to get it to work like new unless someone here can give me anymore good advise to get it to work perfectly
 

Tom F&L GoR

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It will take several trips (3 or more) of complete cool off to full warm up before the idle smooths out. That is the speed at which the ECU learns, so you don't really know the final result yet. You should wait before you do anything; installing a new one will have the same learning process.
 

Jack B

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It will take several trips (3 or more) of complete cool off to full warm up before the idle smooths out. That is the speed at which the ECU learns, so you don't really know the final result yet. You should wait before you do anything; installing a new one will have the same learning process.


How about a little over kill - with SCT you can increase the idle and also adjust several of te de-accelerate parameters. In affect, the IAC function is fully adjustable with SCT.
 
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TorontoACR

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Jack,
What is a SCT. how can I control the idle as I would like to have it idle slightly higher than what it is now due to rattle at idle

How about a little over kill - with SCT you can increase the idle and also adjust several of te de-accelerate parameters. In affect, the IAC function is fully adjustable with SCT.
 

Dan Cragin

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For the idle to re-learn, you must have a fully charged battery that does not drop below 10 volts during cranking. Once the car starts hold your foot on the gas pedal until you can get it to idle without dying. Let the car idle for 5 minutes then turn the AC on and let it idle for 5 minutes. Then drive the car. This should stabilize the idle.

The SCT programmer does not have any end user adjustability unless you have the full software package, this is not practical for most owners.
 

Jack B

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For the idle to re-learn, you must have a fully charged battery that does not drop below 10 volts during cranking. Once the car starts hold your foot on the gas pedal until you can get it to idle without dying. Let the car idle for 5 minutes then turn the AC on and let it idle for 5 minutes. Then drive the car. This should stabilize the idle.

The SCT programmer does not have any end user adjustability unless you have the full software package, this is not practical for most owners.

The whole package is now under $1,000 and it gives you tremendous flexibility. It has done wonders for my car. If you understand a/f programing and the car has widebands you can achieve quite a bit. As I said, merely for idle control, it is over-kill, but, it sure is nice.
 

viper spray

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The whole package is now under $1,000 and it gives you tremendous flexibility. It has done wonders for my car. If you understand a/f programing and the car has widebands you can achieve quite a bit. As I said, merely for idle control, it is over-kill, but, it sure is nice.

tell us more please............:dunno:
 

Jack B

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tell us more please............:dunno:

Dan (Final GTS) sells the package as does Sean Roe. It really is simple it virtually controls all aspects of the PCM. Some of the obvious parameters are, a/f, timing, idle, fan on/off. You can tune both the closed loop and WOT, which is very difficult with a VEC. You also eliminate the inherent delay and possible hesitation associated with the VEC.

If you are knowledgeable you can buy the Pro Racer package and do it all yourself.. If you want a tuner to work on your car you only need the interface, which can be programmed and then used to download the tune to the PCM. Again, Again Dan is probably the best source.

I find it interesting, because I can see the factory base tune. When you see what you are starting with, tuning is a lot easier. I am going to post one of the pcm tables very soon. That table is the a/f adjustment for IAT. A lot of viper owners are trying to maintain a consistent a/f under different temperatures. To do such they are using an offset based on IAT. This table shows the factory multipliers for IAT.

Another interesting point is that when you are tuning for a/f you are always guessing at how much fuel you must add or subtract. That calculation is based upon what the base injector pulsewidth is. You now know exactly what the factory pulsewidth is at WOT, therefore, making the tune process much quicker and accurate. There are general calculations that can approximate base pulsewieth, but, I was not close until I started using SCT.
 

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