IAC Sensor Replacement - HELP !!
Thread Starter
Burning Brakes
Joined: Mar 2001
Posts: 1,228
Likes: 17
From: Mansfield Texas
IAC Sensor Replacement - HELP !!
I plan to install a new IAC sensor this afternoon in my 94 C4. I noted a gigantic vacuum leak in the intake track and the IAC seems to be the culprit. Do you have to do anything special during the installation besides disconnecting the battery. It seems like the end pintle needs to be extended to close up the gap to stop the unneeded vacuum. Does this sensor need to be pre-loaded to set it up properly or do I just screw it in.
Please advise. Thanks.
Please advise. Thanks.
Burning Brakes
Joined: Feb 2000
Posts: 927
Likes: 0
From: Saginaw TX
Re: IAC Sensor Replacement - HELP !! (wheeljo2)
I can't speak directly to the LT1 IAC, but on the L98 you had to have the pintle at a specified number of millimeters out from the body. I think the box had a small piece of paper with the number on it. There may be a short exercise to get the computer and IAC in sync with each other. Your manual is your friend here. Also check the tech tips, there may be something posted there. Good Luck.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: IAC Sensor Replacement - HELP !! (wheeljo2)
There is a safe limit for extension of the pintel before installation that depends on the particular IAC. Instructions came with mine.
Racer
Joined: Jun 2000
Posts: 428
Likes: 1
From: Friendswood Texas
Re: IAC Sensor Replacement - HELP !! (wheeljo2)
The IAC is actually a motorized valve. The PCM opens and closes it (to varying degrees) to control idle speed. It is sort of a computer controlled "vacuum leak". When you discovered it was a source of an intake leak it may have been partially open and looked like a leak.
Adjustment is limited to a maximum spindle extension - see instructions that came with it. I know for L98's it's 1 1/8 in. Install it, start car, then turn it off. Start it again and the computer should have it adjusted. For older cars (like my 86) you have to drive it over 40 mph for more than 3 minutes for the computer to "learn how to idle".
Hope this helps.
Adjustment is limited to a maximum spindle extension - see instructions that came with it. I know for L98's it's 1 1/8 in. Install it, start car, then turn it off. Start it again and the computer should have it adjusted. For older cars (like my 86) you have to drive it over 40 mph for more than 3 minutes for the computer to "learn how to idle".
Hope this helps.
Melting Slicks
Joined: Oct 1999
Posts: 2,501
Likes: 177
From: Houston, Texas FEAR THE BONES
2023 C5 of the Year Finalist - Modified
Re: IAC Sensor Replacement - HELP !! (Mike263)
I wrote a Tech Tip on adjusting the IAC valve on LT1/4 motors. It came from the factory service manual.
