PCM Idle RPM Amnesia

[Fast Too]

Okay, I get my oil changed at the dealer Monday and drive home and all is great. Start the car today to go get a K&N Air Filter recharge kit. The car wants to idle at 1,250 to 1,500 rpm. I tap the accelerator a tad thinking it would slow afterward, nada. So I think put a load on and see what happens, I hit the AC switch and sure enough it puts enough load on the engine to drop the idle below 1,000 rpm. I back out of the garage and let the car warm up. I get to the bottom of the mountain I live on, and there and at subsequent stop signs and traffic lights each time it wants to idle very high around 1,250 rpm. Hitting the AC switch to load the engine calmed the idle down. I get to autozone for the K&N recharge kit and shut the car off. I then turn they key back on and depress the accelerator to the floor for the PCM to relearn the throttle position. Turn the key off and go in and buy my stuff thinking okay when I get home I got to go figure this out. When I start the car after coming back out the problem is gone and never materialized again at stop signs, stop lights etc. It's like the PCM had amnesia over the TPS when I started it up initially before going on my errand. Anyone ever experienced this or should I be waiting for a PCM problem or the TPS sensor to go out?

 

[steveoviper]

Sounds like a AIC motor problem to me.......Air Idle Circut. This is a plugger type thing that opens and closes to allow more or less air into the engine to maintain idle. It sould be located on the air intake somewhere with a set of wires going to it. I have an 06 also, but it is sleeping for the winter......in Wisconsin. Damn snow!

 

[ILLSMOQ]

when my paxton was leaking, oil was getting on the intake air temp sensor and it was making the idle fluctuate.....

 

[Fast Too]

when my paxton was leaking, oil was getting on the intake air temp sensor and it was making the idle fluctuate.....

Mine leaked to as you know, but that was three thousand miles ago with no issues until now........

 

[Fast Too]

okay, so it did it again today. Same drill. Turn car off and then turn key to on position and push accelerator to the floor. Turn key off and then back on and start the car. Problem with idle is gone. I get home after a short drive and decide to pop the hood and look for something obvious. The red release mechanism on the air temp sensor was in the released position although the connenctor was connected. I reseated the connector and pushed the red release into the locked position. I'll let the car sit overnight since that is when the problem seems to occur after sitting for an extended time and try again tomorrow. Hopefully thats what the problem was.

 

[Viper Specialty]

Do you have a single blade throttle body? Or has your throttle body ever been apart?

 

[Fast Too]

Do you have a single blade throttle body? Or has your throttle body ever been apart?

Stock throttle body and no its never been apart.

 

[Fast Too]

Well it would appear that the air temp sensor gizmo really has a function in life. After having plugged it back in properly last night the idle was fine this morning when I tested it. The problems described above only manifested themselves on cold starts. I'm thinking the viper tech at the dealer must have placed his free hand on the sensor and released it by accident when he was either removing or reinstalling the oil fill cap when I had my oil changed earlier in the week. The problems didn't start until the following day after that oil change. Hopefully that is all that it was and the problem won't return.

 

[fqberful]

Well it would appear that the air temp sensor gizmo really has a function in life. After having plugged it back in properly last night the idle was fine this morning when I tested it. The problems described above only manifested themselves on cold starts. I'm thinking the viper tech at the dealer must have placed his free hand on the sensor and released it by accident when he was either removing or reinstalling the oil fill cap when I had my oil changed earlier in the week. The problems didn't start until the following day after that oil change. Hopefully that is all that it was and the problem won't return.

A disconnected IAT sensor should light a MIL and throw a code as soon as you turn the key on.

 

[Fast Too]

A disconnected IAT sensor should light a MIL and throw a code as soon as you turn the key on.

It didn't throw any codes, and it wasn't completely disconnected. Just the locking mechanism was released and it was probably just loose enough to give me heartburn. The problem is gone after reseating and engaging the lock on the connector.

 

[Racer Robbie]

Fast Too:

I have also had the same problems that you describe above with my modded viper. I have the DC ECM tune on mine among other mods so I do not think it is the IAT sensor. I believed the problem was caused by old gasoline that had been sitting in my viper for about 6 weeks when I drove it last month and the idle issue appeared. After I filled up with new fuel the problem went away. Drove the viper last Sunday and no problem. I am going to look into the AIC motor as there may be dirt in the control that needs to be cleaned. This was a huge problem with Chevy V6 engines back in the mid 80's. We used to have to remove them and clean them all the time when customers used non premium fuel. As a side note make sure you guys never loose the red locking tab on the electrical connectors as you can not buy them from Dodge. You have to buy a complete harness.

 

[Fast Too]

Robbie, thanks for the info. Although I haven't been driving as much as I would like because of weather my car hasn't sat any longer than a week and the gas hasn't sat there any longer than 2 or 3 weeks before a fill up when near empty. As far as the AIC motor I'll keep that in mind if the problem resurfaces. I let the car sit again until completely cooled down, started it up and took it for a short drive. Still no more idle issues. I'm pretty convinced at this point that the IAT was just a tad loose with the lock mechanism disengaged and was the culprit.

 

[Limit]

Sounds like a AIC motor problem to me.......Air Idle Circut. This is a plugger type thing that opens and closes to allow more or less air into the engine to maintain idle. It sould be located on the air intake somewhere with a set of wires going to it. I have an 06 also, but it is sleeping for the winter......in Wisconsin. Damn snow!

Where in Wisconsin?