Car threw a CEL today, cyl 1 misfire. Was idling rough when I got to the office. Has done this a few times, but only in the morning.
Same drive home, idles fine in the afternoon.

Pulled the plugs this afternoon & the farthest passenger side & driver's side middle plug had some oil on them. The other 2 were dry. No fouling or build-up on any of them. These are NGK plugs that were installed in October 24 when it threw a misfire, but the far pass side plug had some gunk built up on it.

Just over 1k since my last oil change, checked the oil & still in the middle of the dipstick.

 

Swap coil 1 & 2. Does misfire move to cylinder 2? Do the same for spark plug 1 & 2.
Also clean oil from the two oily plugs with brake cleaner and check the gaps.

 

Is Cyl 1 driver or passenger side?

 

Passenger

 

Thanks, I'll swap that coil with one of my spares when I get home & see how it does.
Cyl 1 & 3 plugs were a bit oily, cleaned them up & it ran better this morning, still a little chugging when I got to the office. Cyl 2 & 4 were dry & clean, though the Cyl 4 coil boot was a bit discolored like it got pretty hot. I don't recall if it was like that when I swapped with the spare set in Oct last year.

Still odd to me, that it runs fine in the afternoon on my drive home.

 

Any new fault codes stored in the DME?

 

I'll have to pull codes & see what comes up.

Swapped coils 1 & 4 with my spares. We'll see if anything changes with that.

 

Good luck!

 

Brief drive after swapping the coils, just a few miles, but nice smooth idle.

 

Well, still an issue somewhere.
I'd cleared the codes & drove enough to get emissions in the green. Passed inspection this morning. 5 min later, CEL is back. Cyl 1 misfire.
May swap the plug & coil and see if that has any effect.

Which is the more likely cause of oil on the plugs, vc gasket or ring blowby?
I'm leaning vc gasket, because there's a small amount of oil on the vc bolt between cyl 1/2.

Edit: Still an issue after swapping to a [older] plug & another coil.
Only at idle, anything over 1k rpm & it smooths out.

 

Are you using a code reader that retrieves BMW codes? If so, what code are you recovering?

Is the oil on the plugs coming from the coil side or the piston side? If it's coming from the coil side, a PCV issue should be considered. If from the piston side, the PCV, piston rings, and valve stem seals should be considered.

Other causes of cylinder 1 misfire could be low cylinder compression or a faulty or clogged fuel injector.

 

Oil is on the spark plug threads of cyl 1 & 3. Not enough to drip but enough to notice.

Sitting in the car now & it's idling perfectly. Haven't changed anything from earlier today when it was idling very rough, enough to throw the CEL.

I'm using a BlueDriver, so it just gives the 'normal' P___ codes

 

You'll generally learn much more diagnostically by recovering the BMW codes.
The first thing to consider for oil on cylinder side of the plugs is the PCV system.

 

Well, swapped plug/coil still misfiring at idle. Enough that it stalled the car in reverse yesterday morning. Anything over 1k RPM and it runs fine. As soon at it drops under 1k, it starts to stumble.

IIRC, the PCV in the VC can be replaced on its own, without needing to replace the entire VC? Could a PCV issue cause just cyl 1 issues?

 

Sitting in the car rider line for pickup at the school. CEL returned.
Scanned & got codes below
Have to hold it over 1k RPM or it stumbles at idle.

 

Check for intake air leaks (intake, EVAP, & PCV system).

 

Nothing immediately obvious on a quick glance. Intake tract as far as I can trace it all looks fine

 

Is the PCV diaphragm split? Any damage to the PCV hose that runs from the valve cover to the rear side of the engine. Also check the hose that runs to the DMTL (EVAP system) pump.

 

Does the PCV cover just pop off?
The hose off the VC looks fine, best I can tell.
Where is the DMTL hose?

 

Yes. Carefully pry it up.

 

Looks good to me, grimy underneath though

 

This image may help.

 

 

Given the 2789 code, could it be just a bad MAF? Would that cause a lean idle condition?

 

Yes. Does it look dirty? If so, try cleaning it with some MAF sensor cleaner.