can an exhaust leak cause a misfire? -
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Go Back > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > can an exhaust leak cause a misfire?

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Unread 06-02-2009, 09:59 PM   #1
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2001 WJ 
Join Date: Sep 2007
Location: Los Angeles, CA
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can an exhaust leak cause a misfire?

CEL came on, and code P0302 showed up -- misfire cylinder #2. i'm aware i do have a crack in my exhaust manifold/header. so i was wondering, could that be the cause of the misfire?

before you suggest, swapping out spark plugs, i've already tried that... twice

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Unread 06-03-2009, 12:21 AM   #2
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While it is theoretically plausible, I would highly doubt it. What motor do you have? If it is the 4.7 check the coil (there is one on top of each plug), that could easily cause the problem. If it is the 4.slow check your plug wires, replace or swap the one giving you problems and see what happens. I don't know the missfire code, so it could be alot of things if that would include clogged injectors and such, but off hand the spark would be where I would start.
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Unread 06-03-2009, 03:55 AM   #3
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Yes it can.
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Unread 06-03-2009, 04:47 AM   #4
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I never got any misfires with my cracked header on my old 4.0L ZJ. I drove it for quite a while with the crack. The misfire is more likely spark or fuel issues. I would change that plug first. If that does not make it go away, then I would change the fuel injector. My money is on the injector.
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