Help chasing down misfire / stumble (29E1 29D0) - 2008 328xi N51
Hello, I have been chasing this misfire for a long time on this car and am reaching a dead end.
I am getting a 29E1 (mixture control 2) code that persists, as well as some misfiring on cold start, which gets worse if I put it in reverse or at stop signs.
Previously I also had a 29E0 (mixture control) and 29D0 (combustion misfire, cylinder 4). I don't see these after replacing my post cat o2 sensors, but I suspect I just haven't driven enough to throw the codes again, as the behavior feels the same.
My new post cat bank 2 sensor is still reading low voltage however (as the previous o2 sensor was). It sits between .1 and .2v after the o2 sensors turn on, while the bank 1 post cat sensor reads between .7 and .9.
Not certain how to proceed from here. Would this be possible short / bad fuse? DME problem? Clogged Cat?
I just had my N51 injectors cleaned and reconditioned, new plugs, new coils (swapped coil 4 with a known good coil and misfire persisted on cyl 4), new MAF, post cat o2 sensors, valve cover, Pierburg Vanos solenoids, check valves, alternator, battery, ground cables, MAP sensor, cam / crank / eccentric sensors, Disa Valves, etc. The valves looked good as well, hardly any carbon buildup.
Any advice would be greatly appreciated.
Posted Dec 29, 2025, 6:31 PM UTC