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So, the past week about i have been having an issue with code p0302 (cylinder 2 missfire), currently got 298k on the clock. Had p0304, p0306, and p0302 and ran a little rough and a bit shakey, checked the sparkplugs and they where pretty worn for 20k ish on them, replaced them and it resolved the other missfires and the missfire counter's where at 0, ran fine, very slight vibration but its always been that way, check engine light came on for p0302 though engine was running smooth and had no power loss, missfire counters for cyl 2 where counting up pretty quickly (as if it was a dead miss), unplugged the coil and no change in engine tone, swapped the ignition coil over too another cylinder and the "missfire" "went away" and came back 100mi later same code, swapped an injector from another cylinder and no change, it only starts counting missfires for cylinder 2 at idle if above 1500rpms ish it says no missfire and the counter stops. I unplug another coil and the engine shakes like it normally does when there is a missfire, engine runs great, good gas mileage. I ended up pulling the passenger side valve cover checking for a knocked off rocker arm and no issues there, valves actuate and close fully, did a compression test 2 weeks ago just for a check up on it and every cylinder was around 140psi (cold). The weird thing is, when ever there is a true missfire it should shake a fair bit and it isn't. Any thoughts? I'm stumped.
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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The OBD2 misfire monitor can detect misfires that we can't notice. Somehow the #2 cylinder is contributing its fair share at times. Being intermittent, it may be a process of elimination to find it.
You might be able to rule out ignition for a cause. That would leave fuel or mechanical as possibilities.
I had seen valve carbon build up issues on these. Does misfire seem to occur when hot or cold?
Seafoam or Mopar combustion chamber cleaner and a bottle of Techron in the tank usually de-carbons well. Try switching to another brand of fuel.


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. . . So, the past week about i have been having an issue with code p0302 (cylinder 2 missfire), currently got 298k on the clock. Had p0304, p0306, and p0302 and ran a little rough and a bit shakey, checked the sparkplugs and they where pretty worn for 20k ish on them, replaced them and it resolved the other missfires and the missfire counter's where at 0, ran fine, . . . .
Look at the oxygen sensor values for the left and right bank along with the fuel trim values for each bank. If the right bank (cyl 2, 4, 6, 8) oxygen sensor values are consistently rich and not oscillating to lean, rich, lean, rich, etc and the right bank fuel trim is consistently negative and constantly taking away fuel, then the problem lies with injectors 4, 6, and/or 8. If one of those injectors is leaking and adding excess fuel, the oxygen sensor feed backs a rich signal to the PCM for the right bank. The PCM will reduce injector pulses (negative fuel trim) for cylinders 2, 4, 6, 8 and try to get it to a lean condition and oscillate between lean and rich. Sometimes the PCM cannot correct sufficiently and the lean condition on cylinder #2 will cause a misfire.
 

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2002 Ram 2500 Quad Cab 4x4 with Cummins. 2021 Jeep Grand Cherokee L Altitude
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So, the past week about i have been having an issue with code p0302 (cylinder 2 missfire), currently got 298k on the clock. Had p0304, p0306, and p0302 and ran a little rough and a bit shakey, checked the sparkplugs and they where pretty worn for 20k ish on them, replaced them and it resolved the other missfires and the missfire counter's where at 0, ran fine, very slight vibration but its always been that way, check engine light came on for p0302 though engine was running smooth and had no power loss, missfire counters for cyl 2 where counting up pretty quickly (as if it was a dead miss), unplugged the coil and no change in engine tone, swapped the ignition coil over too another cylinder and the "missfire" "went away" and came back 100mi later same code, swapped an injector from another cylinder and no change, it only starts counting missfires for cylinder 2 at idle if above 1500rpms ish it says no missfire and the counter stops. I unplug another coil and the engine shakes like it normally does when there is a missfire, engine runs great, good gas mileage. I ended up pulling the passenger side valve cover checking for a knocked off rocker arm and no issues there, valves actuate and close fully, did a compression test 2 weeks ago just for a check up on it and every cylinder was around 140psi (cold). The weird thing is, when ever there is a true missfire it should shake a fair bit and it isn't. Any thoughts? I'm stumped.
Antifreeze level staying constant?
 

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Its your fuel pressure regulator inside your fuel pump assembly. Cylinder 2 is the last in the firing order. The pressure bleeds back. My fuel pressure was good, but turn the key to off and it didn't hold. Replaced the fuel pump and my Cylinder 2 misfire code finally went away. Truck ran the same before and after.
 

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You may want to consider replacing the upstream O2 sensor. The sensor may be failing/lazy but not enough to set an O2 code. The fuel trim noted by AllanC would be beneficial. That all of the misfires are on the same bank indicates a common source. Use OEM/NTK, definitely no Bosch.
 
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