I apologize if my Google-fu is inadequate and information already exists. I can’t find it though so here goes.
2012 550i xDrive, auto.
Everything is pretty much on fleek with my car, it does have this quirk though. Cruise control at 70 or so MPH+ results in this infrequent braking phenomena. The problem is prominent when going uphill making me think it is somehow related to load. I haven’t tried it with the cruise set to 80, 90, more... mostly because it becomes very illegal. My presumption though is that cruising at 90 I’d find the problem to be as apparent as it is at 70 with the uphill component. Without cruise set, the problem doesn’t exist.
The phenomena itself is the car doing brake application. The back end will drop, the real-time MPG goes from 30+ to ~5, and you can simply feel the car drag. The big v8 maintains speed, but you can tell it’s fighting brakes. The phenomena lasts 3-5 seconds then goes away for... awhile. It might occur as frequently as every 20 seconds or so, or as infrequently as never. Seems to be pretty dependent on engine load with a higher load resulting in more frequent occurrences.
Im sure it has the auto brake drying stuff, but this phenomenon occurs in bone dry weather. The brakes are healthy and seem to work well. Where should I look? Long trip coming up and hoping I can rely on my cruise.
Thanks
that's not normal. sounds like a bad sensor somewhere.
That's one complaint I've never heard of. First step would be a proper diagnosis scan by a competent BMW specialist that will communicate and scan ALL the control units, not just the DME.
ASE and BMW Master Certified Technician
Bookmarks