Signature says they have a 535xi and I'm unaware of any of those for E60's having an N55. You need to scan for codes and tell us what you've got. I'm guessing a 30FF underboost code since it seems so common under acceleration, but we really have no clue until you scan it and get us a real code.
A forum community dedicated to BMW owners and enthusiasts. Come join the discussion about Bimmerfest events, production numbers, programming, performance, modifications, classifieds, troubleshooting, maintenance, and more! Bringing the BMW community together.