erratic idle/IAC question. Please help
Thread Starter
Advanced
Joined: Aug 2001
Posts: 61
Likes: 15
erratic idle/IAC question. Please help
My '88 (tuned port indection) idles erratic; cycles between 500-1000 rpm (with or without the a/c on). What is the most probable cause? If it is the IAC, is there a test I can do? I get no error codes. Should I replace it or fix it? Must I remove the throttle body to do so? Please help
Race Director
Joined: Sep 2000
Posts: 12,182
Likes: 1
From: Partying with the Cowboys cheerleaders in Mt. Olive, New Jersey
Re: erratic idle/IAC question. Please help (JDF)
Here's a few areas that might need checking:
1) Timing.
2) Air filter.
3) Air intake manifold.
4) Alternator.
I've had all 4 areas corrected whenever idling problems pop up. Also, see if your local garage perform the MotorVac service. This service cleans years of sludge buildup in the intake system. It's worth the $100.
http://www.motorvac.com
Good luck.
1) Timing.
2) Air filter.
3) Air intake manifold.
4) Alternator.
I've had all 4 areas corrected whenever idling problems pop up. Also, see if your local garage perform the MotorVac service. This service cleans years of sludge buildup in the intake system. It's worth the $100.
http://www.motorvac.com
Good luck.
Instructor
Joined: Jul 2001
Posts: 219
Likes: 0
Re: erratic idle/IAC question. Please help (JDF)
You do not have to remove the throttle body. see my post to Laurie L. a week or so ago. The motor vacs are a good idea but they don't get th IAC circuit well enough. I got down and dirty with a toothbrush and STP throttle cleaner on my throttle body while still on the motor. Pay attention to the sealing surfaces and the back of the butterflys. Let the stuff evaporate abit before starting the motor or you can throw a trouble code. THEN, take it to the Motor vac place. Call around for prices. Jiffy Lube and express Oil do the same thing for $60.
Instructor
Joined: Jul 2001
Posts: 219
Likes: 0
Re: erratic idle/IAC question. Please help (JDF)
Ditto. don't forget to check the vacuum lines to the accessories like cruise control because they also draw off manifold pressure and are often overlooked when someone "changes the lines" :yesnod:
