1985 500SEL Fast Idle after warm-up
 

Hi Everyone
I need some help diagnosing this problem.
At cold start, I do not have a fast idle, about 700rpm
however once the car warms up and reaches operating Temp.
It will idle in neutral at 1100rpm, once in gear it drops down to 700rpm
It seems to me this is just the reverse of what is supposed to occur.

I had the idle control valve removed and cleaned with brake cleaner
as someone suggested but there wasn't any improvement.

Recent work done was a new water-pump and thermostat.
However this problem already existed before the work was done.
Is it the Idle control valve?
Is it the Idle control unit?
Is it the oxygen sensor? (cheap)
Is it the Warm up Regulator? (Expensive)
How do I determine which one it is, without replacing all of them.

Any suggestions would be greatly appreciated.
SilverStar85

check and see how many volts the AIV is seeing while the car is running. Wit the idle that high the ICR should be sending max (12v) to bring the idle down.

If you do not see 12v w/ the high idle I'd wager your ICR is bad.


I'm assuming you have checked the car over for vacuum leaks..


Jonathan