Rocknodd

I have a 97 jeep cherokee sport, i have only owned it for 3 weeks, today on my way to the gym the Rpms dropped to 500 and it wanted to stall out, i gave it gas and got it home. So now it starts up fine but the rpms drop to 500 and it acts like it wants to die then jumps back up to 1000 rpms, I have read a few things to check, but want to see if anyone has had this prob and can save me the headaches. Thanks!

ZINGGG

First and foremost do the easiest thing, clean the Idle Air Control valve. It's a sensor located on the throttle body. Spray it with carb cleaner and scrub it with an old toothbrush. Very common problem when it comes to rough idle.

And one of the first things I'd do when buying a new XJ is do a tune up. Spark plugs, spark plug wires, distributor cap and rotor. Unless you have record of that being done recently.

Rocknodd

Hey thanks for the info. I'll give that a shot today!

tjwalker

Completely agree with the advice of 1996sportXJ.

Tune up.

Clean throttle body and idle air control. But I'd recommend that you not use carb cleaner but use THROTTLE BODY CLEANER as it will not harm the coating on the throttle body. More on that below.

Then see where you are at.
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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

Reinstall IAC and check idle quality

Rocknodd

hey thanks alot guys! i cleaned the IACV it seems to be running better, but still has a slight drop in idle, plug and wires have been changed. so im thinking if the idle dont change its prob a good sign to change it.