[Missionpoole]

Hey friends, maybe I’m just bad at this but trying to diagnose a new misfire issue. What’s strange is it appeared only after changing out my spark plugs but wasn’t super prevalent beforehand. Here’s the context:

2008 bmw 335i / e92

29CC 29D1 29D2 codes

Almost a year ago I did the B58 coil conversion (+ 2 step colder ngk plugs), aftermarket aluminum valve cover/gasket, index 12 injectors, along with a mountain of other maintenance items. Everything worked perfectly to start.

A few months ago I started getting a misfire under WOT and losing oil a bit. Figured the misfire was just the colder plugs going out, and the oil loss I chalked up to the car being 15 years old.

Finally got around to what I thought was going to be a quick and easy plug swap about a week ago. When taking them out I realized cyl 5 and 6 spark plug tubes were soaked in oil. Upon further inspection realized that several of the bolts on the valve cover were finger-loose. I’m not sure what caused the bolts to back out but I figured I would pull it off and replace the valve cover gasket with oem since the one on there is aftermarket (came with the aluminum valve cover).

Installed a new valve cover gasket, put in new step 2 colder plugs, and reinstalled the b58 conv ignition coils (after cleaning out the cyl 5 & 6 coils that were soaked in oil). Put it all back together.

Now when starting the car I have a VERY rough idle, codes for cyl 5 & 6 misfire + the multiple cyl misfire code.

Thought okay, maybe the coils fouled out from the oil exposure so I’ll swap the coils around and see if the issue moves with it. Traded cyl 1 & 2 coils for cyl 5 & 6. No improvement and the misfire codes stayed in cyl 5 & 6.

Not really sure where to go from here… any advice? Should I try to move the plugs also and see if the issue stays in 5 & 6? It’s so weird to me that I had basically zero drivability issues before starting this job so I am lost.

Thanks in advance.

[Missionpoole]

Update:

Swapped the (new) spark plugs from Cyl 5 & 6 with Cyl 3 & 4 just to see if the misfire would move. No luck. Misfire is staying with Cyl 5 & 6 regardless of swapping plugs and coils around.

These are newish index 12 injectors that have less than a year on them, maybe 10,000-15,000 miles, should I be seriously considering that as the issue considering the problem only started after doing the VCG & plugs? Seems like an absurd coincidence.