I second the part about the 2B70-code. My local BMW Dealer told me that these types of codes don't exist on their computers. They're called other stuff and he also told me that they can go deeper in to an error code than non-BMW dealers. If this is true or not, i don't know. Because of the misfirings that occured on my car, i changed my ignition coils on cylinder 6 and 8. I also changed the sparkplugs. Haven't had a single errorcode yet or a misfire.

This operation cost me about $260 and i changed everything on my own since it's basic stuff!