Same problems after new plugs and wires. Help!!
Same problems after new plugs and wires. Help!! Just installed the new MSD 8.5 wires and TR55 plugs and I still have a bad misfire problem. I took it out and drove it around watching the misfire data and found that 1 had 20, 2 had 17, 3 had 92, 4 had 4, 5 had 177, 6 had 344, 7 had 3, and 8 had 4 misfires. The two codes that are still coming up are P0300 engine misfire detected and P0353 #3 coil circuit control. O2's are reading good. Anyone have any idea what this might be tied together by?
Last edited by camarossls12001; Aug 13, 2008 at 12:33 AM.
thinking coils, but find out hwat may have made them go bad. I had that po300 code before. I had an exhaust leak on my passenger side header where the AIR connections are. I swapped plugs wires and coils and fixed the leak and everything was fine
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I am pretty sure it was happening before the flywheel but this has been off and on since I bought the car in 03 with 43K it now has 83K. I changed plugs first time around 60k and found one NGK plug possibly in #5 but not sure the rest had AC Delco's. I think it was the #3 coil that I also replaced because of the same code before first plugs change. I did the wires about 65K. I don't want to steal good parts from one car if this one is just going to screw them up too or I would swap coils.
it can and it did, on my car last summer and this year too. If the leak is in front of the o2 sensors, they will pick up the added oxygen entering the exhaust and try to compensate (the correct air/fuel mixture) by adding more fuel to the cylinders, which in turn fouls the plugs out. FOULED OUT PLUGS = MISFIRE!
PROVE ME WRONG!
If he swaps all the coils to another ls1 and vice versa that may tell something.
Random misfires, every cylinder, think about it.Check his sig too.
then why did I just say it can?!
it can and it did, on my car last summer and this year too. If the leak is in front of the o2 sensors, they will pick up the added oxygen entering the exhaust and try to compensate (the correct air/fuel mixture) by adding more fuel to the cylinders, which in turn fouls the plugs out. FOULED OUT PLUGS = MISFIRE!
PROVE ME WRONG!
it can and it did, on my car last summer and this year too. If the leak is in front of the o2 sensors, they will pick up the added oxygen entering the exhaust and try to compensate (the correct air/fuel mixture) by adding more fuel to the cylinders, which in turn fouls the plugs out. FOULED OUT PLUGS = MISFIRE!
PROVE ME WRONG!
so im guessing its not his plugs...and if its not his plugs then its not an leak right? ^ is the name of the thread. That makes me think he had problems before the plug swap. Which means it still could be coils. When I had his problem i went about it the same exact way he did to fix it. I did plugs first, then wires, and finally bought coils which fixed the problem. The ultimate cause of my problem was one of the A.I.R. tubes which was on the passenger side had lost a bolt and nut. So I had a pretty bad leak right at the very beginning of my exhaust. That fouled my plugs(turned them black, I still may have them lying around somewhere, I may take pics later). LONG STORY SHORT... All of his stuff MAY need changing which includes plugs(definitely), wires(possibly), and in this case coils(definitely).
you should tell your friend to be more specific
seriously dude.
Old plugs were fine the gap was .045 on them (AC Delco Iridiums) I broke one of them taking them out and checking gap so got new ones. Old wires were fine with the exception of the #7 which was rusted at the spark plug connection and broke off when I took the wire off to check it. So thats why I was suspecting bad plugs and wires. Today I checked for loose connectors by wiggeling all wiring harnesses(car running and no change in misfires), checked for bad connection of fuses and blown fuses. Had someone suggest checking for broken valve spring but I think I would have worse problems... Like I said this problem comes and goes and is more noticable when the car is hot and grater than 50% throttle. But than again sometimes no problems at all and it runs great.
yea i would just put on your coils from your good car ( i know its a pain in the ***) on your bad car, fire it up and check for misfires. process of elimination. like others said you won't damage them, so dont worry.