High Idle Problem???

Guys, I just did a Intake Plenum Pan gasket replacement, and then put the jeep back together and it is now idling at 4,000 rpms~!!!


Any Ideas???

If the butterfly is closed and at the idle position, then there must be an air leak somewhere. Did you remove the IAC when you did the work? If you powered up while the IAC was connected and out, the position on the stepper can be way off. Otherwise a good visual check to make sure everything is seated and where it is supposed to be.

Now for the real question. You refer to a Intake Plenum Pan gasket. Are you talking about the gasket that seals the intake to the block and also is shared with the exhaust? My non-HO 4.0 does not have a plenum pan gasket. My 2.5L had a gasket that sealed around the small heater mounted directly below the throttle body. Is that what you are talking about?

No, I have a 5.2l v8, and it has a 2 piece intake plenum with a removable pan, there was a TSB, because the gaskets, failed, which caused an internal vacuum leak..


I put the new gasket on, and new manifold gaskets, and seated and torqued everything to spec... but it still is idling at 4,000rpms..


you think maybe retorqueing the manifold down would do the trick??

would a stuck IAC cause this issue?

I hate to say it but maybe this is a question for NAGCA... They can probably better answer a 5.2L question.

Fixed the problem, I am a total dork...



had the tb gasket on backwards and the IAC wasnt sealed.... All done..