LionHunter
08-21-2021, 05:31 PM
Hey y'all. Been working on a buddy's 328xi w/ an N51. Needed a few services but I'm at my wit's end with a misfire.
Symptoms:
Misfire occurs only at high load, high RPM scenarios. If you never go WOT, no misfire will occur and the car will run fine as normal.
Once the code is thrown, the car goes into limp mode. Restarting the car clears the SES light and it will run like normal.
The misfire codes indicate misfires in cylinder 2 and 5, during testing it also occured in cylinder 4, but only once.
What I've done so far:
The car hadn't been serviced in quite a while, and had one malfunctioning ignition coil, so a full ignition service was done (coils, plugs). Other services include brake pads up front, oil change, a new radiator, a new thermostat, new motor mount bracket bolts, and a new valve cover(PCV outlet was damaged). The car had one bad misfire (at all RPMs/loads) due to a faulty ignition coil, but the sporadic misfires I described above persisted after service.
The ignition coils installed were Bosch and the plugs were NGK (triple checked gapping).
***The misfires were present before any service was performed, and they persist exactly as before.***
I've swapped the coils around and it's had no affect.
I'm beginning to think perhaps it's a fuel injector issue? Otherwise I'm stumped. I'm not sure if there's some N51 specific issue I might be overlooking. What do you guys think?
Thanks ahead of time for any suggestions!
Symptoms:
Misfire occurs only at high load, high RPM scenarios. If you never go WOT, no misfire will occur and the car will run fine as normal.
Once the code is thrown, the car goes into limp mode. Restarting the car clears the SES light and it will run like normal.
The misfire codes indicate misfires in cylinder 2 and 5, during testing it also occured in cylinder 4, but only once.
What I've done so far:
The car hadn't been serviced in quite a while, and had one malfunctioning ignition coil, so a full ignition service was done (coils, plugs). Other services include brake pads up front, oil change, a new radiator, a new thermostat, new motor mount bracket bolts, and a new valve cover(PCV outlet was damaged). The car had one bad misfire (at all RPMs/loads) due to a faulty ignition coil, but the sporadic misfires I described above persisted after service.
The ignition coils installed were Bosch and the plugs were NGK (triple checked gapping).
***The misfires were present before any service was performed, and they persist exactly as before.***
I've swapped the coils around and it's had no affect.
I'm beginning to think perhaps it's a fuel injector issue? Otherwise I'm stumped. I'm not sure if there's some N51 specific issue I might be overlooking. What do you guys think?
Thanks ahead of time for any suggestions!