2007 550, 78000 mi

[KRA]

I have a 2007 550I with 78000 mi with automatic trans. Great car, a thrill to drive but I have noticed that when driving at around 50 mph, I feel (not hear) something that is like the engine losing power or missing for just a second, I can accelerate or slow down and it does not happen again until I go around 45-55 mph. The engine appears otherwise to be running smoothly any ideas? I am afraid to take it to the dealer due to the possibilty that they will tell me I need a new trans?

[Lord Vader]

Take it to an auto parts store or other locations that can scan the OBD system for trouble codes. Most stores, like Advance or NAPA offer to do this for free. If their is a problem with the transmission then its possible a code will be stored, but not have triggered a CEL yet.

[brettski]

Welcome to the Werkz.

I had a very similar issue with my 2000 740iL (4.4l v8) where it would briefly drop and recover <100 rpm at 60km/h and i knew it was happening, so it was bugging me. What solved it (after many other parts were changed ineffectively), was a transmission fluid and filter change. I doubt if your car uses the same gearbox, but its worth a try. Take your car to a specialist transmission service shop and make sure they use the OEM filter and proper fluid, all up it should be around $200 - $300.