Erratric idle when cold

[87blueshelbyz]

I have had this problem for a long time. The car is a 1987 Dodge Daytona Shelbyz, 2.2 turboII, 5 speed. It is stock other than a MP stage II computer. When the engine is cold, when I first start the car, the engine idles fine for about 30 seconds. Then the idle will change from 1,500 rpm to 700 - 500 rpm. Some times the idle will go so low that the engine will stall. This will happen for about a minute, then the idle will smooth out and go back to normal until my next cold start. I have tried different logic modules, coolant temperature sensor, tps sensor, cleaned the throttle body and the ais motor. The engine runs good otherwise and does not have any computer codes to help me to diagnose this problem. Does any one have any ideas as to what could be causing this problem?

[speedfreek500]

These cars will idle 1200 to 1500rpm when first started in the morning when cold. Do you have a scanner? It would be nice to see whet the desired idle is set to. Are you useing the 3 wire O2 still?

When the engine is warm reset the ais motor with the vac line trick.

[87blueshelbyz]

Yes, I have a OTC scanner. The O2 is the factory one. With out looking, It would be the three wire. I have never replaced the O2.

How do I reset the ais motor with the vacuum line trick?

Thank you

[Tbird232ci]

I had a damn near identical issue, which in my case, turned out to be the O2 sensor.

Where are you in Baltimore? I right up by Timonium.

[87blueshelbyz]

I had a damn near identical issue, which in my case, turned out to be the O2 sensor.

Where are you in Baltimore? I right up by Timonium.

I am in Parkville. How did you figure out it was the O2 sensor? Mine appears to be working properly while monitoring with my otc scanner.

[Tbird232ci]

Parkville isn't far at all.

I have a narrowband gauge on the pillar, and I was noticing that it would take a while before it would start to oscillate. When I would start the car, it would linger in the yellow zone, then after 30 seconds or so, the car would start to idle really poorly, and once the sensor started to oscillate, it would idle fine. I figured, since it only has a 1-wire, and it was 9 bucks, I'll toss it on there. Car fired up, idled high as it should, never started to idle poorly, and the sensor oscillated as it should.

Either way, it's never a bad idea to replace an O2 sensor if it's of questionable condition.

[87blueshelbyz]

I am ordering a NTK O2 sensor from rock auto tonight. Even if the O2 sensor is not my problem, it is old and probably has never been replaced on my car.

[ajakeski]

Yes, I have a OTC scanner. The O2 is the factory one. With out looking, It would be the three wire. I have never replaced the O2.

How do I reset the ais motor with the vacuum line trick?

Thank you

http://www.turbo-mopar.com/forums/content.php?206-Base-Idle-Adjustment

[87blueshelbyz]

http://www.turbo-mopar.com/forums/2content.php?206-Base-Idle-Adjustment (http://www.turbo-mopar.com/forums/content.php?206-Base-Idle-Adjustment)

Resetting the base idle did not help the problem. I bought a new O2 sensor, but I am unable to get a 7/8 wrench on the O2 with enough room to remove the old sensor. I am thinking of cutting off the O2 sensor so that I can put a socket and a breaker bar on it to remove it. I will have to wait until I get my Jeep back from the dealership so that I have another vehicle to drive, in case I run in to problems removing the old sensor from the swingvalve.

run

[ajakeski]

You're going to need to heat that oxygen sensor with a torch to get it loose.

[87blueshelbyz]

The oxygen sensor was not my cold idle problem. It still does it with the new oxygen sensor. The engine does seem to run a little smoother. I not know where else to look to try to solve my problem.

[tryingbe]

Set your OTC scanner to look at the VSS speed. If the VSS is bad, your car will idle funny.

[87blueshelbyz]

The VSS on my scanner matches the speed of my speedometer. My car has the same symptoms as this old post below that I found through google. Several other people have had this problem and no one else has appeared to have solved this issue.

http://www.turbo-mopar.com/forums/showthread.php?6727-Idle-oscillating-at-start-up

[shadow88]

Is it low on coolant?

[87blueshelbyz]

No, the coolant level is fine.

[RoadWarrior222]

I have had this really intermittently, usually when it's actually occurring, it goes away with a brief tap of the pedal... slight oxide on TPS after sitting a while? who knows... I do notice it more coming into fall though and I wonder about "gas changeover" meaning we get low vapor gas for summer and high vaporising gas for winter, and somewhere in between, it's a little cool to be ideal for the summer blend.