Idle too fast

[fastcw]

I have a '91 with 13,400 miles. It has always been a little slow to idle down to 800-900 rpm since I bought it with 11,400 miles on it.

Now the idle is very slow to come down to 1000-1100, and while I'm sitting at idle, will jump back to up as high as 1500-2000 for a second before dropping back to 1100 or so. Rarelly goes down below 1100 now.

Any ideas?

[Sgreg]

GM has a replacement prom which brings idle down. Don't have # but someone will.

[tomtom72]

I don't know the # but over at the netreg site is all the info ya need!

16193416 BTW, discontinued.

[tccrab]

My '90 used to idle a little high, I bought a Haibec chip and it's been
perfect since.
There is a difference between stopped idle and idling as the car is moving.
When you're rolling up to the stoplight it will idle at around 850 or so, when the MPH goes to 0 the idle goes to 650 and stays there.
That being said, a prom may help you and maybe not if you've got a big vacuum leak.
A very large vacuum leak will cause your idle to be high, have you done any leak checking?

[Gunny]

Originally Posted by tccrab

A very large vacuum leak will cause your idle to be high, have you done any leak checking?

I agree