Misfire on Cylinder 4
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From: WI
Misfire on Cylinder 4 so i scanned my car with odb2 and got a misfire on cylinder 4. swapped the coil packs and didn't change anything. swapped the fuel injectors and now getting random/mutiple misfire detected. code p0300. Does anyone know what this could be or where to start. I have changed all plugs wires also after this started.
Thread Starter
Teching In
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From: WI
I tried swapping wires on plugs and nothing still. had same code with the misfire on cylinder. and i also checked and double checked the plug that they are snapped. had a code p0304 when i had misfire cylinder4 now p0300 when random misfire
I'm really just guessing but I am betting on a coil. Not sure how much one is but you could replace them one at a time with the new one, it may not be too expensive. Try to put a ohm meter on each wire also and test them also. Seems to have changed after swapping injectors, that doesn't make much sense to me but I am no expert. Hopefully someone chimes in, google that subject also maybe something will come up. Good luck. Post back your findings.
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Thread Starter
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From: WI
sounds good will do, also if anyone else has any ideas please help this is my baby and hate her running this way right before i was going to start all mods. I was told maybe the lifters were bad but after a lot of research i highly doubt that this would be the issue but not 100% positive.
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random misfire is thrown when it detects misfires on more then one cylinder, try clearing the code, see if the misfire code comes back for the coil you switched and if it moved to a different cylinder. If it stays on 4, you have to look at the spark plug wires, which you can ohm check with a multimeter, the spark plugs, and the fuel injectors and harness. Does your harness show signs of degradation, as in the loom is starting to get brittle and break apart? Check those areas for signs of rubbing through wires etc. I had areas where my harness started to rub through when i first bought my car with 100k on it as the loom on the harness was falling apart.
Thread Starter
Teching In
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From: WI
replaced all plugs and all wires. just did a spark test on all plugs and has spark everywhere so all coils see to be throwing spark. also did compression test on fuel and everything stayed stable. checked injector wires and all getting electricity as well. looked at harness havent had time to pull the whole heat sheild off yet but from what i could see there was no damage to any wires so far, but will look for that also.
That was a section of the main harness that ran above the intake manifold, I believe that wasn an injector wire that was damaged on mine. If the injector seems to be the source of your issue, you might want to either have them replaced (rockauto.com) or have them cleaned and flow tested (osidetiger.com)
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From: WI
im getting 65lbs when i fuel tested today so think fuel is ok. Im so lost on this wish this was my old 81 Monte Carlo would have had engine out and rebuilt by now. i will get one new injector and see if there is any difference with that swapping out the injector i swapped from 4 to 6 to make sure that doesn't change anything. otherwise all coil wires seem to be fine. this is so perplexing i dont want to beleive that its a lifter as i dont think that the mechanic did a through testing of everything but spending 2k just to have the back replaced seems a little risky not knowing for sure
You can run injector cleaner right thru the rail, that is much cheaper and a lot less work plus no down time than removing all the injectors. Did it on an Iroc and it worked well. Worked just like an a/c charge kit.
im getting 65lbs when i fuel tested today so think fuel is ok. Im so lost on this wish this was my old 81 Monte Carlo would have had engine out and rebuilt by now. i will get one new injector and see if there is any difference with that swapping out the injector i swapped from 4 to 6 to make sure that doesn't change anything. otherwise all coil wires seem to be fine. this is so perplexing i dont want to beleive that its a lifter as i dont think that the mechanic did a through testing of everything but spending 2k just to have the back replaced seems a little risky not knowing for sure