Brandon1985

My jeep will idle high in park I will drive it around after a few minutes it will die and it will start back up and die again shortly after

tjwalker

1. Start with a thorough cleaning of both the idle air control and the throttle body. They get carboned up over time and miles. More on that below.

2. Be sure tuneup hardware is fresh. Plugs, wires, cap, rotor, fuel filter

3. Test and adjust your throttle position sensor. They are a common failure on the 87-90 4.0 engine.
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The Idle Air Control (IAC) is mounted on the back of the throttle body. 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

Reinstall IAC and check idle quality

Brandon1985

Thank you I will try that today!

Brandon1985

Thank you man that fixed the problem perfectly!

tjwalker

Glad I could help, but exactly what fixed the problem? Cleaning of the throttle body and idle air control?

Brandon1985

Yes I did both and put some sea foam in the gas tank

Brandon1985

Jeep just died on me had to tow it home sputtered out and will crank but will not start back up do u think it could me the fuel filter?

tjwalker

Best to start a new thread for a new problem/new owner. You will get better replies.