High Idle
Thread Starter
Burning Brakes
Joined: May 2008
Posts: 1,008
Likes: 5
From: Greensburg PA
High Idle
Ever since I bought my 91' a few months back it's had a high idle. During winter It'd idle around 1000 rpms, now it idles around 900. I thought you could adjust it manually, but IIRC I read it's electronic(computer) controlled and can't be adjusted. Where should I start looking?
Le Mans Master
Joined: Oct 2004
Posts: 6,314
Likes: 508
From: South-central Missouri
Ever since I bought my 91' a few months back it's had a high idle. During winter It'd idle around 1000 rpms, now it idles around 900. I thought you could adjust it manually, but IIRC I read it's electronic(computer) controlled and can't be adjusted. Where should I start looking?
Start by seeing if you have a "vacuum leak". Pull the snorkel off the air horn and place a hard cover book over it while it is idling and see if it will remain running. If it does, you may have a leak.
Then too you might want to inspect your idle air controller to see if it is gummed or carboned up.
P.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
If the IAC is stuck too far closed the car will likely start but will stumble a lot and not want to idle until it warms up. If it's stuck too far open you'll have a high idle. If it's somewhere in between you may have a little of both.
If you decide to look into this as a possibility you want to be very careful with the IAC, they can break pretty easily. The IAC can be removed with the TB on the car, but if you can easily remove the TB you can clean it better. Remove the IAC and carefully clean the passages with throttle body cleaner. When cleaning the pintle on the IAC itself be careful, you don't want to retract or extend it or you may damage the motor, just clean it carefully with throttle body cleaner. An old toothbrush helps.
If you remove the TB it's a great time to clean it up in general and make sure your throttle blades aren't sticking as this can also cause a high idle.
Thread Starter
Burning Brakes
Joined: May 2008
Posts: 1,008
Likes: 5
From: Greensburg PA
I did some reading about IAC's and how careful you have to be with them. I'll have to buy a new TB gasket and clean the TB and IAC. The car is a 91' with 45k on the odometer. The P.O. didn't drive it much at all, so I'm trying to sort small stuff out.
Thanks for the insight, and I'll post updates on the car when I get a chance to clean it.
Thanks for the insight, and I'll post updates on the car when I get a chance to clean it.
