I know this is an old thread but I am having an odd issue and want to rule my MAF out as a cause. I have a 02 E55 and I am getting -18% fuel trims (less then 1% difference left to right) with my new MAF module.
I have post my original question in this thread but I am not getting any answers
http://www.peachparts.com/shopforum/showthread.php?t=210103
Thanks