Iac
Thread Starter
Racer
Joined: Sep 2005
Posts: 304
Likes: 1
From: Carson City Nevada
Iac
I was setting my minimum idle on my 88 and noticed somthing strange. With pin B grounded on the ALDL, the IAC motor continued to make noise. I thought I could wait it out and it would stop in the correct position, but it never did. Has anyone else noticed this? Normal or bad IAC?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
There's no reason to play with the screw. The common spec is 400 +/- 25 rpms at x inlet air temp at x relative humidity. The Dilbert who calculated it never published the temp and humidity part, but GM (and all the other OEM's) set the screw for that number. From there, all the infinite variables work. At best, you'll turn the screw few times and get back to where it was. At worse, you'll screw it up and get the intermittent driveability issue from hell. If the throttle body is dirty, clean it. If there's an air leak replace it.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The linkage bends over time and the throttle stop screw digs a hole in the lever when the throttle slams shut and hits it. It needs to be readjusted from time to time. I didn't think so until my car started dying at idle. Doing the minimum idle adjustment fixed that.
You're supposed to disconnect the IAC connector, shut off the ignition and remove the ALDL A-B jumper before restarting the engine and setting the screw. Otherwise the ECM will try to adjust the IAC to control the idle speed.
You're supposed to disconnect the IAC connector, shut off the ignition and remove the ALDL A-B jumper before restarting the engine and setting the screw. Otherwise the ECM will try to adjust the IAC to control the idle speed.
Last edited by Cliff Harris; Apr 23, 2012 at 05:04 AM.
Thread Starter
Racer
Joined: Sep 2005
Posts: 304
Likes: 1
From: Carson City Nevada
I did disconnect the IAC and remove the jumper. The IAC was just making noise up until I disconnected it. I was just wondering if it was suposed to stop moving on its own.
Last edited by 87FIREREDRAGTOP; Apr 23, 2012 at 08:56 AM.
Thread Starter
Racer
Joined: Sep 2005
Posts: 304
Likes: 1
From: Carson City Nevada
There's no reason to play with the screw. The common spec is 400 +/- 25 rpms at x inlet air temp at x relative humidity. The Dilbert who calculated it never published the temp and humidity part, but GM (and all the other OEM's) set the screw for that number. From there, all the infinite variables work. At best, you'll turn the screw few times and get back to where it was. At worse, you'll screw it up and get the intermittent driveability issue from hell. If the throttle body is dirty, clean it. If there's an air leak replace it.
Team Owner
Joined: Jan 2003
Posts: 20,254
Likes: 221
From: Summerland B.C. Canada
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