My uncle is having extremly high hot idle. Around 1400rpms. Is there anyway to adjust this?

This is all the info I have been given for some strange reason, and the rpm range was hard to drag out.

Thanks

 

Are all the hoses on tight. I THINK that if a hose or vacuum line is lose or not on at all it can cause the idle to be high. But I'm not 100% on that.

 

wanting to "buck" into gear is another vac line symptom. an easy way to test is wit some carb cleaner around the base of the lines. a change in rpm is an indication of a leak. from there id ask when it was last tuned up, etc. any more info is always helpful.

 

thanks for the sugestions. I will pass them on and see what other info I can squeez out of him.

It is a 98 4.0 if that makes a difference

 

Vacuum leak is suspect here. Perform a comprehensive search for one! Follow the tip above from VTJeep on looking for this.

After that, the next task is to clean the throttle body and idle air control. Such a common problem that I have a "cut and paste" procedure all ready! Here it is.
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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