BMW XM Engine Smoke and Emergency Mode Crisis

I experienced similar issues with my 2020 BMW X6 M. The symptoms were nearly identical, jerking, smoke, and reduced power mode. Turned out to be carbon deposits in the combustion chamber causing pre-ignition. Had it diagnosed at a dealership specialist. The problem required a thorough fuel system cleaning and removal of carbon deposits from the valves and chamber. It was quite a serious issue that could've led to engine damage if left untreated. The procedure involved removing the intake manifold and cleaning each cylinder individually. After the service, the engine ran smooth again, no more jerking or smoke. These symptoms shouldn't be ignored, especially in a high-performance engine. I'd suggest getting it checked by a BMW specialist who's familiar with M powertrains. They'll need proper diagnostic tools to confirm if it's knock-related.

Thanks for sharing your experience with the X6 M issue. It's really helpful since I'm seeing such similar symptoms in my XM. I'm planning to take it to a specialist as you suggested. Would you mind letting me know roughly what the repair cost you back then? Also, have you had any related problems pop up since the cleaning was done? Just trying to get an idea of what I might be dealing with.

Hey again! Happy to give you an update on my X6 M situation. I actually just had it fixed last week, cost me 425 € for the whole carbon deposit removal and cleaning job. And I've got great news, the knocking issue is completely gone! The engine's running super smooth now, no more jerking or smoke when I accelerate. It was definitely worth every penny because these high-performance engines need proper care. Since the cleaning was done, I haven't had a single problem, it's like driving a new car again. The specialist really knew what they were doing with the carbon deposit removal. Just make sure you find someone who really knows BMW M engines. They need special handling, and not every mechanic has the right experience. Good luck with your XM, you'll be amazed at the difference once it's sorted!

Just wanted to update everyone on my XM situation. Finally got it sorted at a specialist mechanic who really knows their BMW M engines. The whole ordeal turned out pretty similar to what was suggested, carbon deposits causing all that drama with the jerking and smoke. They did a complete fuel system cleaning and got rid of all the carbon buildup in the chambers. Cost me about 500 € but totally worth it. The engine's running like a dream now, no more emergency mode warnings or power issues. Feels just like when I first got it. Funny thing is, while I was there, the mechanic showed me how much gunk had built up in there. Pretty shocking for a new car with just 7025 km, but apparently it can happen with these high-performance engines. They also gave me some tips about fuel quality to help prevent it from happening again. Really appreciate all the advice from everyone. If anyone else runs into similar issues with their XM, definitely don't wait around like I initially did. These engines are too nice (and expensive) to risk any damage. Now I'm just happy to be back enjoying those smooth rides again!