Misfire 0302 Any Ideas???

rmp608

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Hello, was hoping someone else has had this same problem. 2010 Liberty 120,000 mile. The last 6 months I keep getting the 0302 misfire code. When I check with my scanner it also shows both banks long term fuel trim -12% and -14%. Almost always at startup when it has been sitting overnight. So far replaced...throttle body...new plugs and wires..all new injectors..new map sensor..new crank sensor..new O2 sensor (only on bank 2 upstream)..new coolant temp switch. The car runs fine after warming up and after clearing code does not come back the rest of the day.. Thank you for any possible help!!!!
 

LibertyTC

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Generally cyl #2 misfire is related to either the spark plug or coil pack. What wires?
Do you have the correct spark plugs installed?
The KK 3.7 v6 utilizes NGK ZFR6F-11 Gap is .043 inch
 

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LONGJEEPOWNER

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I had the same issue on my 2010 Jeep Liberty. I changed the coils and NGK spark plugs and problem solved. The only issue was later on down the road it appears to have moved the problem to the catalytic converters. Changed the O2 sensors with no luck. Eventually I had to change the Y pipe with the cats. Problem solved. I have 180,000 miles on it.
 

rmp608

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I had the same issue on my 2010 Jeep Liberty. I changed the coils and NGK spark plugs and problem solved. The only issue was later on down the road it appears to have moved the problem to the catalytic converters. Changed the O2 sensors with no luck. Eventually I had to change the Y pipe with the cats. Problem solved. I have 180,000 miles on it.
Did your code go away on its own at any time? On mine after clearing the code and getting warm.. the car runs fine and light does not come back on. I did the carb cleaner spray around the intake test..no change..PCM ??
 

lfhoward

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^^^ yes. My 08 has 6 coil packs, but in 09 or 10 they changed to having 3 coil packs, with each one serving 2 cylinders.
 

sleazy rider

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My bad! I’m running the first version (KJ) and even google can be wrong. When I searched the result showed coil packs. Sorry!
 

lfhoward

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My bad! I’m running the first version (KJ) and even google can be wrong. When I searched the result showed coil packs. Sorry!
I wonder if it is a cost savings for Chrysler to cut the number of coils in half. It would make diagnosis easier because you’d have two simultaneous dead cylinders.
 

sleazy rider

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Hmmm, looking at those oddball coils, I wonder if one side could go bad but still allow power to the other bank…. Think I’d be checking the coils! 95% of the time, its the issue for that code.
 

lfhoward

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Hmmm, looking at those oddball coils, I wonder if one side could go bad but still allow power to the other bank…. Think I’d be checking the coils! 95% of the time, its the issue for that code.
I guess that might be possible! I don’t know at all how they’re engineered so what I said about 2 dead cylinders is an assumption.
 

rmp608

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update.... Turns out I had a leaking head gasket!! Not about to start ripping apart the motor...I changed the plugs again..and put the Blue Devil head sealer in...no more misfire...no more engine light..Hope it lasts for a least a year..
 
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