[danili16]

Hi all,

I have a 2012 M3 6MT with ~57k. Since I bought it back in 9/2022, it’s had one issue, with another developing recently.

1) When warmed up and at idle, especially after driving for a while, the RPMs will suddenly drop and then bounce up/down for ~10-15s before either stabilizing or stalling (restart is fine). This doesn’t happen or worsen after refueling. No other patterns of note.

2) Back in October, I got a horrible miss followed by an engine malfunction/SES. Codes were for bank 2 O2 sensors, and misfires were for all bank 2 cylinders. The misfire cleared on the next restart, but now comes back intermittently after a hot start and lingers for a minute or two, then suddenly clears. Interestingly, it hasn’t re-triggered the SES/EM lights.

For further context, when I got the car, it had high-flow cats/aftermarket O2 sensors/tune. Carvana ended up paying a *ton* to replace both cats, all four O2s and re-flash the car. The O2s have all been replaced a second time under warranty. I’ve also since replaced the spark plugs and moved coils around, both to no avail.

Only codes that ever come back now are misfires.

Anyone ever experience something similar? Either issue related, you think?

Appreciate any insight!