Idle surges up and down

[Jim]

This is my 2nd Eclipse and third fuel injected car that has an issue with the idle wandering up and down. It fluctuates up and down at stop lights. It doesn't stumble at any other times other than idling. I have a '90 GSX. The fast idle doesn't seem to work either. Might they be related? I understand there is no cold start injector on these Eclipses? Should I look for a vacuum leak? It doesn 't do it all the time though. Thanks!

[Bryan Savage]

Clean the throttle body and turn the Basic Idle Set Screw down. Done.

[rlarsen]

It's it slowly wandering, or does it jump up and then drop about once every couple of seconds? It's probably your ISC. Could be FIAV.

[Jim]

Thanks for the help and good advice. It is a slow wandering, intermittent surge up a couple hundred rpm and then down. :)

[prophecymiller]

I was too having the same problems with my car about a month ago. The solution I found to it and now it idles rock solid at 750rpms was just the fact that the throttle linkage was too tight. I scanned my car with a Genesis and noticed that at idle the throttle position sensor was showing off idle when it should have been on. I just gave the linkage a little slack at the adjustment on the back of the intake manifold and then it showed on at idle and off as soon as I gave it any gas just like it is supposed to. It took no longer than two minutes for an easy fix without trying to change parts to no avail... good luck!

Steven

[BlueVelocity]

If it's a 1G like in the pic, Datalog it. I'd agree with Ryan, the few dozen i've seen do this was almost always a bad ISC.

Steven has the right idea as well, if the idle switch is inactive, or the throttle body has no ground, this happens too. (looks at Erik A.)har-har

Erron S.

[Muck_diesel]

does your check engine light come on for a short time?

[Muck_diesel]

do you have an after-market bov on it?