Engine seems to lose revs and dies at idle.

[AviP]

So I got the snake out of hibernation and now the engine seems to lose revs when I'm idling or slowing down at a stop light and then dies.

Diagnosis so far:
The battery does not seem to be the problem as it is fully charged and only 6 months old.
The alternator doesn't seem to be a problem either since the voltage was in the high-13V to low 14V range.
The fuel is fresh.
No check engine light or diagnostic messages on the dash.

So what could be causing this? I have only 29+K on the odometer. Help!

Avi
1997 Viper GTS

 

[DrumrBoy]

Is this after its warm or only when cold?

 

[Indy]

Did you have the battery disconnected? Might need to relearn the idle.....start her up and let it rev at about 2000rpm for a bit and then slowly reduce the revs....might take a few driving cycles to get it set up right. Also, are the battery terminals clean - check for corrosion or wire damage. Did you charge the battery fully? Could be that the battery lost some power over winter or were you using a battery tender? Hope you find the problem. Good luck.

 

[ViperTony]

To relearn the TPS voltage after disconnecting/reconnecting the battery:

1. Turn the key/ignition to the "On" position without starting it.
2. Press the gas pedal all the way down to the floor and hold it for 3 seconds.
3. Repeat 2 & 3, three more times.

Turn off. Start the Viper and enjoy.

 

[GTSHolgi]

To relearn the TPS voltage after disconnecting/reconnecting the battery:

1. Turn the key/ignition to the "On" position without starting it.
2. Press the gas pedal all the way down to the floor and hold it for 3 seconds.
3. Repeat 2 & 3, three more times.

Turn off. Start the Viper and enjoy.

That's what I did when I set her free. Had no issues, was expecting some rough idling or similar but it ran like the day I sent her to the "garage jail".

 

[AviP]

Drumrboy,
This was after it's warm.

ViperTony,
I'll try the TPS trick and let you know.

I did get a successful OBD inspection today for DMV registration purposes.

-Avi
1997 Viper GTS

 

[Hoosier Daddy]

Needs a few drive cycles on it to re learn the idle setting. Battery charge must have been low at one time.

 

[95Viper]

I had the exact problem a long time ago and it was the Idle Air Control module. Passenger side, two screws mounted to intake, tube going to airbox. Removed, took apart, cleaned with carb safe sensor, installed. Also removed intake tubes opened butterflys, cleaned all around inside even with toothbrush to ensure the throttles snap closed. Ran perfect afterwards.

 

[AviP]

Thanks guys. The TPS trick seems to have solved the problem. Now that it has learned it, the engine does not stall at idle. Thanks.

-Avi
1997 Viper GTS

 

[HotRodMojo]

Hey guys, I am having this same problem (low idle and dies when stopped and engine is hot) and want to try to do the TPS trick to see if it works for myself also. Question is ViperTony says "repeat 2 & 3, Three more times." This quote is #3. Does he mean repeat 1 & 2, as in the ignition needs to be turned on and off each time the gas pedal is all the way down? Or just leave the Ignition ON while the gas pedal is depressed down all 4 times?

Also, I have a AEA Tuner on my Viper. Not sure if it matters or not.

Thanks if anyone can clarify.

'97 GTS

 

[ViperJohn]

Leave the ignition on when repeating the throttle actuation.

You may also have a bad IAC motor. It controls air flow when at idle. It is essentially a worm gear that can get a little lazy with time. When you are driving it closes and opens to allow vehicle to idle. The IAC also needs some time to adjust especially if the vehicle battery voltage got low. (IAC = Idle Air Control)

 

[HotRodMojo]

Thank you Viper John for clarifying. I am going to give it a try tonight.

 

[troublemaker]

Lots of good advice here. The best advice that I have gotten is to do the throttle relearn, let it idle for 10 minutes or so then turn the AC on and let it idle again. I am not proud of the amount of times I have had to do this, if I got better at remembering to plug the trickle charger in I would probably lose this skill set.

 

[HotRodMojo]

Well the TPS re-learn didn't do the trick. I took it out for a joy ride and noticed it didn't want to idle as low with the AC off. I'll give troublemakers advice the next shot. I just this GTS from an out of state dealer. Good guys. They told me they will find someone local in North Houston area to get it worked out for me. But if I can fix the issue just by a simple idle, I rather of course. It is an extremely strong running car and I love it. Just tired of heel towing it at stops.

'97 GTS Venom 650R

 

[HotRodMojo]

A big shout out to troublemaker. It solved my idle issue. I took it out for a spin last night through the neighborhood and the engine RPMs never went below about 1K. Before, I was going all the way down and dying on me. That is the good news. The bad news is I noticed when I pulled in the garage and it was idling, I saw the oil light flickering some. I had seen it do that when the idle was very low, but now it is around 1K. Maybe time that I start a new thread.

 

[ViperRed]

You may also want to check all your Injectors for any possible O-ring leaks.