This is a 2.0-L engine with about 102K miles. When the engine is fully warm idle surges and is low rpm, sometimes dropping momentarily below 4-500 rpm. I have read the posts in this forum indicating the IAC (idle air control) valve as the cause. I removed the connector from mine and when fully warmed up there was no change to the idle. If I do that before the engine is fully warmed up the idle drops significantly. The engine runs fine at above idle or when accelerating.

Since the valve is obviously working prior to the engine being warmed up all the way does this mean the problem is not the IAC valve itself, but perhaps there is some other component that sends a control signal or voltage to it that is faulty? I can't imagine there is anything inside the IAC that needs cleaning since if the valve were stuck or the solenoid open or shorted it would not work at the cooler temps either, right?

Input appreciated. Are there other tests I can do?

Thanks,

Dave

 

removing the IAC and cleaning carbon off the tip of the plunger did not make any difference.

 

Hi, Try replaceing the spark plug leads andfit long life spark plugs. Clean the trottle body too. Let me know how you get on

 

Paulie,

All that was done long since. It helped some but did not resolve the problem.

Thanks for the suggestion,

Dave

 

Hey I had the EXACT same problem! Mine turned out to be a leaking intake manifold gasket. Check out Good ol idle problem for my fix.
Cheers
Vaughan