Good Afternoon,
I recently took my 2000 XJ to a local shop. I had them replace the valve cover gasket that was excessively leaking oil. On the way home I noticed it was idling rough and running lean. Called the shop and they had me bring it back by to look at it.
I was told there is an exhaust leak now causing issues. Could an exhaust leak cause rough idling and running lean. It almost sounds like if they removed the throttle body, there isn't a secure seal. Thoughts on replacing the throttle body gasket? or any similar experiences with solutions?

 

I'd have a look and see if they knocked any vacuum lines off. Exhaust leaks wouldn't make it run bad.

 

Spray some carb cleaner around the TB and listen for idle change, if you're not sure.
(Yes it's good practise to replace the thin TB gasket if the TB is removed)

 

I removed and cleaned the TB and the idle acv. Replaced the TB gasket and seems to be running fine now. No more check engine light. I think there is a small crack in the exhaust manifold due to the sound.

 

Happy days

 

Any update, is everything good now?


 

See post #4.

Routine recommended maintenance for the win once again!!!CRUISER'S MOSTLY RENIX TIPS

THROTTLE BODY AND IAC CLEANING

OCTOBER 30, 2015 SALAD 28 COMMENTS EDIT
Originally by TJWalker of CherokeeForum & JeepForum



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 retracted, the air control passage flows more air which raises the idle speed. When the valve plunger is extended, 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. This should be part of a normal tune-up procedure and whenever idle/stalling issues are present.

CLEANING THE JEEP 4.0 IDLE AIR CONTROL

1. 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). On ’91 and later, it may be easier to just remove the whole throttle body. Be sure to use a new throttle body to manifold gasket when reinstalling.
2. “Gently” wiggle out the IAC from the throttle body. Gasket/O-ring on the IAC can be re-used if it is not damaged
3. 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 oxygen sensors. 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.
4. Thoroughly spray clean and flush where the IAC seats in the throttle body with the same spray cleaner.
5. It is also a good idea to clean the entire throttle body bore itself, the butterfly valve inside of the throttle body and it’s edges, and all associated linkage as long as you have things disassembled.