larryftmfw

Ok guys some quick questions. Iv been having a very erratic idol, sometimes the jeep is hard to start, and the acceleration hasn't been as great. Could this be a bad tps? Or maybe just a dirty throttle body?

larryftmfw

Replaced the tps, the idol control thing was dirty too so should I replace that?

tjwalker

Always post year/engine.

Did the new TPS fix your symptom?? Try this procedure
---------------------------------------------------------

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

larryftmfw

04 4.7 v8. I did clean it. All my symptoms are gone. Except the idle is still lightly erratic. How much does a new iac cost?

tjwalker

Not sure for a V8. Most of us XJ guys have the 4.0 inline 6 cylinder engine. How fresh are your tuneup parts??

Check rockauto.com

or for genuine Mopar parts, go here:

https://www.moparonlineparts.com/

larryftmfw

The iac had a ton on carbon buildup. I got it pretty clean but I feel like a new one would be better! Is far as tune up parts I'm not sure. I'm a new owner to the jeep.

tjwalker

Install fresh tuneup parts. You have no idea how many miles are on yours. New parts establishes a baseline for future maintenance.

larryftmfw

What all should I replace?

Jennifer

Did you fix your problem? My 96 Cherokee is having the same problem! I cleaned the throttle body, replaced the TPS & Cleaned the IAC. Now I'm boggled. Maybe I should just buy a new IAC?

larryftmfw

I replaced the tps, cleaned the iac. It's not as bad but there's still something wrong. My idol randomly drops to 3-400 rpm. So new iac for us

Jennifer

That's what I'm thinking too. I think they are under $50 bucks. I'm thinking also vacuum lines. I might have a leaker?? I'm gunna check those and if it don't work I gotta try the IAC. Let me know if that works for you.

larryftmfw

I sure will, my vacuum lines and my gaskets for the throttle body need replacing

larryftmfw

Just got my new gasket. Well see if that does the trick.