2012 328XI E90 Bank 2 misfires and other oddities


Hi, I’m new here, this is my first post in any forum, anywhere, anytime actually, so go easy on me lol. I’ve had kind of a strange series of events that has left my car, basically undrivable, if I feather the gas (25% or less) I could probably drive around all day, (although I’m not) if I get on the gas at all, the CEL starts blinking, the car shakes, loses all power and won’t recover until I pull over and restart it. (fuel pump?) I have multiple codes and I’m not sure if they are independent problems, or all coming from a single failure point. I’m furloughed because of the pandemic, so I don’t want to start throwing money at things without a logical reason to do so. At this point I’m overthinking everything, and I’m hoping someone here can send me down the right path without wasting too much $. lol Thank you in advance for any input, and I’ll try to include everything that has happened with the car related to misfires in case it is relevant.

Codes
2C9D – Oxygen sensor heater 2 before catalytic coverter: Activation
2A7A – Variable camshaft timing control, exhaust, cold start (always got this code and it goes away on its own)
29E0 – Mixture control
29E1 – Mixture control 2
29D’XXX’ – Combustion misfires cylinder 4,5,6

Around 70k miles the car was misfiring, I don’t remember which cylinders but it was all over the board, not specific to bank 1 or 2, I moved coil packs around and the misfires followed, so I replaced all coil packs. I went cheap hoping I’d get lucky, but knowing I might not.

I didn’t… The car ran great for maybe 200 miles and #2 began misfiring, I replaced #2 and a couple hundred miles later #5 started misfiring, then another cylinder… eventually I got what seemed to be a good set of coils in the car and it ran perfect for quite a while. (would have been cheaper to buy the oem’s right off the bat, lesson learned)

This doesn’t relate to the misfire prob I’ve been having, but idk if I may have damaged something so… One night the car needed oil, I stopped and picked some up. It was like 40 degrees, pouring rain and dark. (excuses) I was freezing my @$$ off and in my rush I didn’t replace the oil cap. :rolleyes: 10 miles down the freeway the car started violently shaking and completely shut down. I had it towed home, popped the hood and realized what I had done. I replaced the oil cap and the car didn’t recover. I reset the computer by connecting the +/- overnight and it was back up and running perfectly.

Fast forward about 6 months with absolutely no problems. I took the car on a 1,400 mile road trip to Yellowstone. No problems on the way there, but when we got to the Rockies, aprox 8,000′ and above, there was violent shaking, misfiring, etc, I was constantly pulling over to restart the car, at which point it would run “just ok” until another elevation change. (of course I attributed this to thin air, but expected a BMW, or any modern car would be able to adjust to this on the fly) On the way home (back at normal elevation) there was a lack of power and slight stuttering under heavy acceleration.

Upon return, it degraded quickly and we were back to random misfires and essentially undrivable. I repaced all coil packs and plugs with OEM and it was still misfiring. I read the codes and the misfires are now specific to bank 2 / #’s 4,5 and 6 and don’t follow a coil pack or plug if swapped out.

Here’s where I’m lost and not sure where to start.
Is it normal for coil packs to go at only 60-70k miles, or is there something else going on that caused them to fail and could explain why the “cheap” replacements kept randomly failing?
Why wasn’t it able to make adjustments to the high elevation, does this point to a faulty o2 sensor?
Is the 29E1 related to an o2 sensor? If so, am I correct in thinking that doesn’t necessarily mean the o2 sensor is bad? Wouldn’t a lean or rich condition for any reason such as unspent fuel due to misfires, cause the o2 sensors to read outside the expected parameters and throw a code?
I moved all coil packs and plugs to see if the problem would follow, I haven’t yet moved injectors and probably won’t unless someone thinks I should, but it seems very unlikely that all injectors in bank 2 would fail at the exact same time.
With the amount of misfiring problems I’ve had over time, could that unspent fuel have damaged the cat? or something else?
Because of the way this problem kind of slowly changed over time from random misfires to specific bank 2 misfires, I’m having a hard time focusing on where the problem is. Any help redirecting me down the right path would be very much appreciated. Thank you.



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