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MCG 05-23-2007 08:47 AM

Idle Problems
Mine its a 00' 4.0L ,5 spd.
When I first started in the morning took longer than usual to start,actually I had to push the gas harder to make it run,When it was cold couldn't stay on Idle it stalled righ away unles I leave th rpms @ 1000,but after warming up,well I drove it to my job like 20 min from where I live,and I try to keep in idle and it stays but around 150 or 200 rpms,way to low,any sugestion? fuel pump,ECU,any idle control censor??
other wise the Jeep runs good ,the only problem is whe i leave the gas and the car stalls or stays in very low rpms.

Any sugestion,or similar experience?
Thanks a lot guys.

JCS05Rubi 05-23-2007 09:00 AM

If you have a TJ, you are fuel injected and should never need to give it gas to start on a normal operating engine.

With that said, there are numerous things to mess with your idle; fuel injectors, ECU, sensors, vacume lines, intake/exhaust obstructions, idle air control etc etc.

I would start with the idle control and Catalytic convertot first just to rule them out. Most likley its the idle control.

Take a rubber mallet or your hand (when cold) and hit the cat, or exhaust pipe real close, and see if it rattles (shouldnt)

Remove your intake tube, make sure nothings in there. Pull your throttle body and clean it out, paying particular attention to the idle control shaft thing.

Take your jeep to someone with a scan tool and see if anything obvious shows up on real time data stream

my .02

Jerry Bransford 05-23-2007 09:15 AM

I'd first guess a dirty IAC (idle air controller). The IAC is what meters air into the throttle body at idle since the butterfly valve that lets air into the engine at other times is closed at idle. Take it off (it's only held on by two small T-25 bolts) and gently clean its solenoid-actuated plunger with carb or throttle body cleaner and a rag or brush. Clean the throttle body oriface it meters air through too.

MCG 05-23-2007 09:17 AM


Originally Posted by JCS05Rubi (Post 84691)
Take a rubber mallet or your hand (when cold) and hit the cat, or exhaust pipe real close, and see if it rattles

Yes It does,I forgot to mention that.I heard that cat. rattles when I shut off the engine or in normal idle,like any broken cat.
I hope may be is just that the problem.


JCS05Rubi 05-23-2007 09:26 AM

It may just be the heat shield vibrating, not the honeycome inside. Make sure the cat is actually bad before you replace it. A bad cat will effect driving at speeds also. Usually feels like your towing a battleship anchor.

Thanks Jerry, I couldnt remember if the whole throttle body had to come out or not. I figured he could clean it all up while he was at it :)

MCG 05-23-2007 10:11 AM

Ok guys thanks a lot ,Later on I will go to my friend's shop and I will print out your posts and I will try to find the problem. I will post later what was the problem.


Jerry Bransford 05-23-2007 10:16 AM

Just in case, the IAC is located on the passenger-side of the throttle body.

MCG 05-24-2007 08:42 AM

I seems like it was a dirty body throtle, I just drop some carb cleaner and after that It works just normal,the Jeep didn't throw any code.
Now its working .
Thanks again.

Fourthwolf 12-07-2013 12:50 PM

I had a similar problem with my 2000 TJ 4.0L bogging down when idling. It would stall out if I didn't throw it into drive after starting the engine. Removed the throttle body and IAC and cleaned them off and now it idles fine.

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