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Jeep backfiring

815 views 7 replies 4 participants last post by  zuki_06 
#1 ·
Yes, I've searched didn't find quite what I was looking for so here it is. 96 Cherokee 4.0 auto, 135xxx backfiring and stumbling, misfiring badly. I have chased it down to cylinder one. Getting spark, changed injector still backfiring. Valve/lifter noise is loud also, anyone have any ideas? Fuel pressure is spot on.
 
#2 ·
Got a CEL? Idk if 96 would have it or not but my 98 I had it back firing into the intake. I found an "over boost" code which after hooking my vac gauge up indeed did prove It wasnt back firing into the exhaust like I thought. Ended up being my upstream O2 the one up by the engine. Also check compression and if you have one do a cylinder leak down test. good luck
 
#3 ·
Not sure on the CEL, but mine is showing bank 1 lean. And it is only backfiring from cylinder 1, when I unhook the plugwire it no longer pops. And I just replaced the upstream O2 sensor made no difference. Got till memorial day weaken to figure this out! Or I'm going wheeling on 5 cylinders!
 
#6 ·
I'm thinking your right and it's the a valve problem. If I was to take this wheeling like it is would it be allright to just unhook the fuel injector harness to this cylinder? Or would that cause more problems?
 
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