287jeepcherokee's

Hello, i have an 87 jeep cherokee and it hasn't been licensed for 7 years we just relicensed it and have been driving it (it didn't sit for 7 years we drove probably at least once a month just around our property) but anyway its back on the road now and it's having an idle problem like when you push the clutch in coming to a stop the idle will drop to 400 or 500 rpms and come back up or sometimes just die all together. Now when restarting it will rev to 2000-2500 rpms and stay there for awhile. this is expecially annoying in parking lots did some searching and heard it could be iac? not sure if it is though! Any help would be greatly appreciated.
Thanks
Joe

cruiser54

First off, make sure your intake manifold bolts are snug. Secondly, look for damaged vacuum lines on the engine.

287jeepcherokee's

Okay will do i have already checked all vacuum lines i found one broke but i repaired it but it didn't appear to make a dfifference. So ill check intake

287jeepcherokee's

Okay there all tight and can't seem to find any vacuum hose leaks. But the jeep seems to do it randomly i drove it a couple days ago and it was fine idle would drop down pretty low when coming to a stop light but it never died, nor did it's revving thing. So do you think the iac could be going out?

cruiser54

Do this before replacing stuff:

Courtesy of TJWalker:

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The Idle Air Control (IAC) is mounted on the back of the throttle body. (front for 87-90) The valve controls the idle speed of the engine by controlling the amount of air flowing through the air control passage. It consists of a stepper motor that moves a pintle shaped plunger in and out of the air control passage. When the valve plunger is moved in, the air control passage flows more air which raises the idle speed. When the valve plunger is moved out, the air control passage flows less air which lowers the idle speed. Over time and miles, the IAC can get carboned up which can have an adverse affect on idle quality. Cleaning the IAC may restore proper function and is an easy procedure to perform and good preventive maintenance so it is never a bad idea.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

Remove the air filter cover, associated hoses and the rubber boot that goes from the air filter cover to the throttle body. Remove the IAC with a torx driver (2 bolts; one can be kind of hard to get to)

"Gently" wiggle out the IAC from the throttle body. Gasket on the IAC can be re-used if it is not damaged

Clean the IAC with a spray can of throttle body cleaner; inexpensive and available at any place that sells auto parts. Throttle body cleaner is recommended rather than carburetor cleaner as it is less harsh, safe for throttle body coatings and is best for this task. Use cleaner, a rag and a toothbrush and or Q-Tips. Be gentle; don’t twist or pull on the pintle that protrudes from the IAC as it is fragile and you could damage it.

Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner

It is also a good idea to clean the entire throttle body itself, the butterfly valve inside of the throttle body and all associated linkage as long as you have things disassembled