Quote:
Originally Posted by Jakesax
I have this issue with my 2018 m50d and my main dealer and local BMW specialist cannot diagnose it.
So far it's had, new EGR, new inlet manifold and transfer case serviced 2 weeks ago.
After the service I didn't notice the tugging/missing which usually occurs at low revs regardless of speed (can happen at 30 in town or 80 on the motorway). I am now starting to notice it again.
No one can really advise where to go next. I've paid for the BMW extended warranty but my dealership are saying nothing is wrong and I can't replicate it on demand to show anyone.
It's getting to the point now where I'm thinking about getting rid, the car runs fine other than that it's just annoying that a car of this age with 39k miles on the clock should be doing it.
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As mention above but it seems to be if ignored:
Check your transfer case.
Here is what happens when your transfer case goes out of calibration:
The DME asks the transfer case to set a certain torque within the internal clutch packs in the transfer case.
The servo motor in the transfer case responds and adjusts the clutch packs.
The DME then looks for a very small percentage of acceptable wheel slippage between the front and rear tires.
If this is not within spec, the DME tells the servo motor to release all pressure on the transfer case clutch packs and start over.
This entire process happens very quickly and will get stuck In a loop if out of calibration.
The rapid engagement and disengagement of front wheels creates a "tugging" or "missing sensation" that can happen at any speed.
Many threads on how to fix yourself: 30min transfer case oil change plus ISTA to recalibrate or some foxwell scanners can (530 can If memory is correct)
BMW techs are not trained to test or calibrate transfer cases. If you are not a DIY person, you MUST specifically ask them to perform recalibration test. Most will just want to sell you a new one for 8k when a simple oil change and recalibration will fix.
F15/16 owners get screwed that most transfer cases now don't have oil drain plugs so you must siphon out. Some dealers refuse to do this and just want to sell you a new one for 8k because $$$.