[6spdTanzM4]

I have read all these posts on the misfires and took the car in to the dealer three times for this issue. Tonight though I am happy as I got the car back with no misfires, jerking, or rough idles after driving 40-50 miles. Same initial issues as everyone else here. In the end I ended up with 6 all new (updated version) injectors and 6 new plugs and that seems to have done it for my car. Here is the timeline for how it all went down if it helps anyone else:

09 335i with 40-41k miles when the rough idle started, all stock.

Visit 1. First visit was a combo of this problem and scheduled maintenance. The dealer said they are aware of the issue and will follow their procedure to work it out. To start with under scheduled maintenance they were replacing all the plugs and would wait to do anything else, and actually couldn't because the car wasn't throwing any codes. This didn't fix anything and actually seemed to make things worse.

Visit 2. Took it back in and told them it wasn't fixed. So they kept it for 2 days and told me this time there were misfire codes on the 2nd bank - cylinders 4,5,6. They replaced the injectors in this bank only, because I guess per BMW they won't get reimbursed for the work unless the car actually throws codes. Get the car back - no change, same problem, they can't do any more.

Visit 3. This time I read the codes myself after a week and it threw H29D1, H29D0, H29CC, which are codes for misfires in specific and multiple cylinders. *Do not clear codes on your own, just read them* If you clear them the dealership will not be able to do anything. This was also a day after factor warranty was up - but if you schedule it beforehand then your warranty is still in effect fwiw. This time they ran a bunch of diagnostic tests, swapped some coils around to make sure those weren't the problem, and put new updated injectors in the first bank - cylinders 1,2,3. They also took out the 3 plugs they just put in and installed 3 NEW NEW ones. This seems to have done the trick.

This was Murray BMW in Denver and in the end they were great about the whole thing. The retail price on their work and parts was over $4,000 which was all under warranty. They said that since it's a known issue BMW has been known to goodwill this kind of work for free also, so keep pushing your dealer if you need to.

I made about 6 pages of notes from this post along with a list of parts that everyone mentioned and gave them a little packet. Not sure if it helped or not but it would give them some clues potentially as to what to check.

Will update this post if anything changes or if misfires or rough idle comes back.