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Unread 09-21-2011, 07:13 PM   #1
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1991 XJ Cherokee 
Join Date: Jun 2011
Location: Virginia beach, VA
Posts: 13
89 xj 4.0 misfire

Okay well today, i went out to re tighten my intake manifold bolts since it seemed to be idling high. I just did this a few months ago and dont drive it very often, the back half of bolts where all loose again with the very back one being able to be tightend with your fingers. When i started it back up, it was misfiring and wont stop. I know i have a very frayed cps sensor cable that when i move it, causes the jeep to cut off. Could this be my problem? It did this the last time i tigthend up the bolts but cleared up. A freind doing body work on it for me, also adjusted my idle screw without me knowing because it was idling high due to the intake being loose. I have a few broken vaccum lines as well but the jeep has run fine since i bought it like that. Any ideas? All answers are greatly apreciated

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Unread 09-21-2011, 08:11 PM   #2
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2014 JK Wrangler 
Join Date: Dec 2010
Location: Hell, PA
Posts: 2,495
My XJ had a miss right around 2500 RPM's but once I hooked up all the proper vacuum lines it disappeared. Did you start in the middle of your manifold and tighten your bolts outward going top to bottom? Replace the broken cable as well...if all of these issues don't fix it then there is something else wrong.
2014 JKU Rubicon *DAILY DRIVER*
Gone but not forgotten; 2005 LJ *SOLD* 1987 XJ *SOLD* 2002 WJ *SOLD* 1995 ZJ *SOLD*
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Unread 09-21-2011, 08:28 PM   #3
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1990 MJ Comanche 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 10,878
Fix the vacuum lines and the CPS wiring as they are known problems. Why look elsewhere first?
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