Contour Enthusiasts Group Archives Forums General Troubleshooting goofy idle when cold

Ok, here's the deal: When cold, start the car, revs rise to about 2k, then fall to 4-500, nearly stalling then shoot back up to between 1500-2000, then fall back down, etc. Eventually it will settle itself down, sometimes it will stall. This condition will happen about 50% of the time, with the other 50% being trouble free. If I start the car and get the crazy idle, I can shut it down & restart to solve the problem. Same thing if it quits...start it back up and it's fine.

This condition will only last for a minute at most. Warm starts and regular driving are fine.

I've had a CEL light for some time, finally cleaned out the EGR passages this past weekend which seems to have taken care of that problem. Have yet to run new codes.

Any thoughts on where I should look? MAF? ISC? I just cleaned the ISC when I had the EGR system apart so I know it's clean. I'm also running a Weapon R intake...there's no place for the IAT sensor so I just have it hanging free near the filter. Could that give me troubles?

I dont think I can help you specificaly, but some food for thought:

Sounds like one of two things, when you first start the car, it is on a "outside loop" control, and runs on preset. once the O2 sensors reach an appropriate temp, the ECU switches to "inside loop" control, using all sensor inputs to regulate the idle speed mixures, ect.

Sounds to me like either the ECU is getting a bad tempurature reading form one of the sensors (intake, O2 or Coolant temp), or it cant decide to go "inside loop" or "outside loop" and is switching between the two.

I really cant provide much more assistance than that at this point, if someone has seen this before, please feel free to expand on this.

Interesting you mention coolant temp. On a cold start the low coolant light will come on. It goes off after a couple minutes. The coolant level is fine, so I'm assuming there's something wrong with the sensor. Hmmmm, perhaps the problems are related?

This sounds very likely, the other condition for switching to closed loop mode is coolant temp. I suspect you have a flaky sensor....

Clean your throttle body.

Just cleaned it a few days ago.

I'll check into the coolant sensor, thanks for the input!