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Old 05-09-2012, 10:57 AM   #1
mindhunter's Avatar
Join Date: Sep 2011
Posts: 64
4.0L XJ Misfiring.. please help

Ok so I have a 99 Cherokee XJ that has the same 4.0L as my TJ Wrangler. It started misfiring/hesitating and idling really hard so I took it to the shop. They spent 3 days looking at it and decided that it needed a new crank sensor and throttle body. They also fixed in a leak in the vacuum hose. I got it home and it started doing the same thing again. They said to bring it back and they will continue to look at it, but I was hoping some of you engine savvy men and women might be able to give me some insight into what it might be. Might save me some money if I point them in the right direction.

I looked it up and some people said that it could be dirty fuel injectors, dirty cylinders, and/or bad spark plugs. I'm pretty sure it is misfiring in all but one cylinder. Thanks in advance for your help!

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Old 05-09-2012, 04:20 PM   #2
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Join Date: Jun 2011
Location: Williamsburg, VA
Posts: 141
My 96 XJ did that once. Didn't throw a code for quite a while.
Turned out to be one of the oxygen sensors.


2012 BFG JKU Sport S
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Old 05-09-2012, 05:28 PM   #3
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Join Date: Sep 2011
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I read that too, but I changed the O2 sensor that threw the code and it made the check engine light go off. But the misfiring problem is still there.
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Old 05-09-2012, 08:05 PM   #4
Join Date: Oct 2006
Location: Eastern IA
Posts: 217
Check your engine temp sensor. It's on the front of the engine where the radiator hose connects to the water neck on the head. They are only like $20.
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Old 05-09-2012, 08:28 PM   #5
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ok I will do that. Thanks
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hard idle , hesitation , mechanic help , misfire

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