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Cyl #5 and #6 misfire

D

Droopy76

NAXJA Forum User
Location
Tazewell Va.
My brothers 2001 XJ has a misfire on 5 and 6 that I can't get rid of. New coilpack, plugs and cranksensor. No luck. Scantool says front three cyl. are running rich. back three are running lean. Do I have injector problems or O2 problems? Also when I tuned it up there was a giant rats nest in the airbox. Clogged intake runners maybe? I like the ignition system on my 98 better. Somebody help me brainstorm please!
 
Sounds like a plan. Though the rats nest consisted of the entire filter. The only thing that wasn't chewed up was the rubber gasket and the wire mesh. All the paper was in a big clump. The jeep is new to my brother. Bought it about 2 weeks ago. Ran fine for about the first week. I just wonder how much of that crap made it through the mesh?
 
Swapped injector 5 and 6 with 1 and 2 also changed #6 spark plug. Still got a cyl #6 misfire. Only misses at idle and starts kinda hard. Checked the fuel pressure. It was running about 48psi. Help!
 
What did the plug look like?

Compression test might not be a bad idea here. See how 5&6 compare to the other cylinders.

Don't want to rule out an internal problem as a possibility.
 
Last edited:
I'll second the CCR and a hot leak down test.

I do the Cranking Compression test cold but do the leak down with the engine up to temp as per the FSM.

If I weren't Senile, I post up a link to the thread where I typed in the proceedure. It is here though...
 
Swapped the injectors around and changed #6 plug. Still #6 misfire. #5 misfire went away before I did all this. Fuel trim is running about right on the front three cyl. About -11% on the rear three cyl.
 
Pull the throttle body and see if there's anything visible inside the intake. Compression test should help give you a much better idea what really up. Do you see any wires chewed at all?
 
Already checked the injector plugs with a noid light. I havn't done a compressin test yet. Gotta remember to bring my gauge home from work. With the fuel trim being so outta wack im thinking either something in the intake or
o2/cat issues. What do the guru's think?
 
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