97, 2.0 with a poor idle at operating temp.

[Hoags]

My daughters 97 with a 2.0 auto trans has developed a very poor idle condition after reaching operating temps. It runs just fine when cold and once normal temp is reached the RPM drop real low to a point of intermittent stalling. If the A/C is turned on it does help a little but the RPM is still low. I have searched for vac leaks and have not found any, I am not saying that there are no vac leaks I would bet that that is the problem, I need some ideas as to where to look for a vac leak that would develop at op temps. Or any other suggestions as to what may cause the poor idle condition. Any help is greatly appreciated.

Thanks

[Davescort97]

I think you're right about the vacuum leak. They can be hard to find. Check the PCV valve and hoses, especially the 90 degree fitting on top of the engine. The elbows have been known to have a crack. If the PCV valve has never been replaced, do that lst. Check the check valve in the vacuum booster hose. You should be able to blow in it one way, but not the other way. If you can blow through it either way or not at all, it is bad and should be replaced.

The IAC (idle air control) on top of the throttle body could be needing cleaned or replaced. It allows extra air into the engine whenever it is cold or has an addiltional load placed on it like the AC. If the idle is helped some by turning on the AC, then I'd think the IAC is trying to do it's job. Take the 2 8mm head size bolts out and clean it with carb cleaner, then spray it with WD 40.

Hey, I"ll back up here. Put a vacuum gauge on the intake. If the reading is 18 or above, then you probably don't have a leak.

[Hoags]

Thanks for all the suggestions, I will give it all a look as soon as I can. You have given me a direction to look rather than going at it blind and doing a hit and miss attempt. I will post up any results as soon as I have a chance to look at her car early this week.

Thanks