Cranky ALPINA B7

[TxGR8White]

Need some suggestions please:
ALPINA B7 (N62 Engine, Supercharged), 100,000 miles. Car showed a CHECK ENGINE light while on a trip, pulled into BMW dealer to have
codes read and verify it can still be driven a little further. Codes came back for O2 Sensors (Pre-Cat) and engine exhaust temp sensor failure. Bought both O2
sensors, the exhaust temp sensors and replaced them. While I was at it, the car got new plugs and ignition coils. Drove great for several weeks and then while
trying to pass another motorist, shifted down to M4 and the car stumbled briefly - CHECK ENGINE flickered and after a few miles came on steady. Pulled into the
Rest Area, turned the car off, turned it back on and it was normal again. I had my laptop with INPA loaded on it and read a CYLINDER 2 Misfire. Cleared codes,
car ran smooth for another 2 weeks. Car now has a rough idle, but no codes, when I restart, the idle is smooth again for a few minutes, but it is taking less
time with each start for the rough idle to come back. Threw a code this evening showing #2 Misfire ( I had switched coils the last time, so I know the coil is
good.

I am thinking possible fuel pump, injectors and/or fuel filter - I am looking for suggestions if there is something I am overlooking? The error
codes are not helping. Both banks run with identical values when it comes to cylinder contribution, exhaust temp, intake temp, etc.

Could this be a MAF issue? If so, would it always point to #2 cylinder? How about crank position
sensors? They are just reed switches, but can these "go bad"?

Hoping someone can help me see a bit further, as I currently have a bit of tunnel vision.

Thanks in advance.

[billh]

Since you have done the coils/plugs AND swapped the offending cylinder's coil with another (Did you swap the plug as well??). I would look at fuel.

MY B7 has had injector cleaner (Techron) every 4th tank for the past 50k miles. That is the ONLY reason I didn't look at the injectors when I had huge misfire issues in December ( I believe it ended up being a bad tank of gas).

Run some techron ASAP and see if it helps.

Bill

[TxGR8White]

I did swap the #2 coil and plug (forgot the plug in the original posting) with #1 coil and
plug, but still got a #2 Misfire Code. Took it out last night and did a "spirited" acceleration on the on-ramp to the interstate, and the engine had a
very slight stumble, threw a CEL. Went back to the house and the codes were "Multiple Cylinder Misfire - #2, #3. I am thinking injectors now or possibly
fuel filter. Can someone point me to the fuel filter ? (or filters - I am new to the E65

Thanks

[TxGR8White]

UPDATE:

- Replaced fuel filter-fuel pressure regulator
- Replaced fuel pump assembly
- Replaced Thermostat (threw that code -P0128- early Friday morning)

goes like a bat out of hell again!