I own a 2009 335i xDrive (N54), 6spd. Not to hijack your thread, but I had the exact same problem come up recently with the cold fall weather. On cold and 'wet' mornings, my car would be running on 4 or 5 cylinders until it warmed up. It would stutter and sometimes eventually stall producing misfire engine codes P0300 (multiple misfires), P0301 (cyl 1), P0304 (cyl 4), etc.
I contacted BMW asking if this could be a HPFP issue, quoting the 10yr 200k Emissions Warranty. They said they had never heard of it, and there is no such warranty on the car. I did some more research on the web, found the TSB's.. and I wrote them an email quoting about a dozen Youtube videos of people stating it was their HPFP on the fritz (showing the same symptoms as what I had). I also included a note from BMW Canada regarding the warranty, and suddenly they changed their tune. My car is currently out of warranty, but after speaking with the service manager she agreed to bring my car in for some tests.
Before bringing it in, I then tried swapping a coil pack from cyl 4 to cyl 1 to see if the Check engine would follow, and to my delight IT DID. I called BMW, said thanks but let me try and figure this out before I waste your time any further on my out of warranty car... I ordered 2 coil packs, replaced them and again to my delight... the next day my car started just fine!!! WIN, right?
Wrong. The next day it comes back again, this time Cyl 1 was misfiring again with the new coil pack in there. For fun I tried swapping the coil back to Cyl 4, and no change. Within a few minutes, my car starts puffing white and blue smoke out the tail pipes. Thick, THICK white and blue smoke. A moment after that, OIL is coming out of my tail pipes. I shut down the car and had it towed to BMW yesterday. They're still doing diagnostics, but I'm going to follow up on here and let you know what I find.
Personally, I think it's an injector problem. I think an injector is stuck open. There was a TSB and voluntary recall on them for cars built 04.02.2007 to 10.31.2008... My car was produced 13 days later on November 13, 2008, so technically it shouldn't be the same problem.
Last edited by Husband; 10-29-2013 at 06:49 AM.