96 Cherokee 4.0 Intermittent idle problem.

[72mino]

My jeep is acting like the IAC valve/motor is bad, but not all the time. It won't idle without giving it a little gas somtimes. It may start up fine and I can drive for 5-10 minutes, stop at a light and it will die; or it may act up when I first start it. It will usually go back to idling right after driving a while, but it may or may not last.

I pulled the IAC valve and cleaned the carbon build up off of it as well as the hole it goes in as well as I could.

Can IAC valve be intermittent like that, or could my TPS be going out so it doesn't know when I let off the gas completly for the IAC to take over?


Dustin

[sector95]

Dustin,

IAC is run with a servo motor ...so, yes, if the motor is in its death throes then it could give a quirky idle. And spraying it down with carb/intake cleaner will usually make it worse if it gets into the motor.

Cleaning the throttle body can work wonders; my suggestion would be to remove it completely from the engine so you can get every passage thoroughly clean....it's relatively easy to take off and put back. Good idea to use a new gasket ...same with IAC.

Your TPS can be checked with a volt/ohm (VOM) meter to see if it's resistance varies smoothly through its sweep.

I would also do a thorough check on any vacuum lines ....in fact I would just replace any of the rubber lines ...make sure you use hoses rated for "fuel/vapor" ...straight rubber hose used for washer or vacuum applications will rot out if used for fuel vapor applications. Also check for potential vacuum leaks at gasket connections ...with the engine running, use a little carb cleaner to spray on suspect connections ...if the engine idle goes up, you gotta leak.

Hope this helps ...good luck.

Mike
00XJ