F10 M5 constant misfire

[jturner]

Hey, I'm having an issue with my m5. Constant but very slight misfire at all rpm's - but the car still pulls incredibly hard. I've unplugged each coil individually and found cyl 4 on bank 1 makes no difference. Swapped with a known good coil from another car and still misfiring. Plugs are only 6000km or so old. exhaust has quite a "fuely" smell to it. Got an injector on order, but could anyone confirm if they've had this before and what the culprit was?

There are no codes. I've also tried the ISTA individual fuel injector shut off and cyl 4 doesn't do anything when turned off, so im 100% sure there's an issue regarding that cylinder. Im just not sure what…

[fstm5]

Originally Posted by jturner

Hey, I'm having an issue with my m5. Constant but very slight misfire at all rpm's - but the car still pulls incredibly hard. I've unplugged each coil individually and found cyl 4 on bank 1 makes no difference. Swapped with a known good coil from another car and still misfiring. Plugs are only 6000km or so old. exhaust has quite a "fuely" smell to it. Got an injector on order, but could anyone confirm if they've had this before and what the culprit was?

There are no codes. I've also tried the ISTA individual fuel injector shut off and cyl 4 doesn't do anything when turned off, so im 100% sure there's an issue regarding that cylinder. Im just not sure what…

Spark plugs ? Or MAF sensors? Could be something small like that

[jturner]

Originally Posted by fstm5

Spark plugs ? Or MAF sensors? Could be something small like that

I'm gonna clean the mafs and see. I'm just confused as to why there's no codes, and wouldn't that cause a misfire on pretty much all cylinders?

Engine was rebuilt about 6000km ago and had new spark plugs so not sure…

[fstm5]

Originally Posted by jturner

I'm gonna clean the mafs and see. I'm just confused as to why there's no codes, and wouldn't that cause a misfire on pretty much all cylinders?

Engine was rebuilt about 6000km ago and had new spark plugs so not sure…

My bad I didn't read the post clearly I didn't know you're misfiring on one cylinder, but yes dirty maf's can cause some hiccups I wouldn't say misfires but you never know

If you're having slight misfires on one single cylinder it could be anything from a bad injector to bad coil , plug etc

[jturner]

Originally Posted by fstm5

My bad I didn't read the post clearly I didn't know you're misfiring on one cylinder, but yes dirty maf's can cause some hiccups I wouldn't say misfires but you never know

If you're having slight misfires on one single cylinder it could be anything from a bad injector to bad coil , plug etc

I swapped with a known good coil from another car and still misfiring. I suppose I better check the plugs and clean the maf but given the spark plugs are fairly new I'm not sure it's that. I'm thinking injector but I'm just pretty worried about it