BMW 8 Series Engine Knocking: Power Loss & Smoke Issues

Hey there! I have some experience with BMWs and had a similar issue with my 2021 BMW 7 Series (I also owned a 5 Series before). From what you describe, it sounds very familiar. My car showed similar symptoms, knocking, power loss, and that annoying jerking during acceleration. Took it to my regular workshop and they found deposits in the combustion chamber. The whole repair, including cleaning and labor, set me back about 425 Euro. After the fix, it ran like new again. Could you share more details about your error codes? Also, how many miles/kilometers are on your car? This info would help me give you more specific advice based on my experience.

Thanks for sharing! My 2023 BMW 8 has 188563 KM on the clock, and I just started experiencing these issues shortly after my last service. Your combustion chamber deposit issue sounds quite similar to what I'm dealing with. The knocking and power loss are really concerning me. Did you notice any specific patterns when the symptoms would get worse? Like during cold starts or after the engine was warm? I'm trying to gather as much info as possible before heading to the workshop. Good to know about the repair costs too, helps me prepare for what might be coming.

Hey again! Great to hear back from you. Yeah, with my BMW 7 I definitely noticed some patterns. The knocking was actually worst during cold starts, especially in the morning. Once the engine warmed up, it would get a bit better, but the power loss and jerking were still there during acceleration. The symptoms in my case started getting more frequent after about 180,000 KM, pretty close to where you are now. It's interesting that yours started after a service, in my case, I'd been using a different fuel brand for a while before the issues started, which might have contributed to the deposit buildup. One thing I didn't mention in my first reply, before getting it fixed, I tried running some fuel system cleaner through it, but it didn't help much. The workshop explained that the deposits were pretty severe and needed professional cleaning. The whole job took about a day and a half, but it was totally worth it. Since you're at similar mileage to when I had my issues, it really does sound like the same problem. When they cleaned my combustion chamber, they also recommended changing the spark plugs while they were at it. Added a bit to the cost but made sense since they had everything apart already. Let me know how it goes at the workshop, I'm curious if it turns out to be the same issue!

Given the context, Thanks so much for all those details! It's super helpful to know about the cold start issue since I've noticed exactly the same thing, definitely worst in the mornings. I'll skip trying the fuel system cleaner then, since you mentioned it didn't help much. I've booked the car in for next week, and I'll definitely mention the combustion chamber deposits to them. Makes sense about changing the spark plugs while they're at it too, might as well do everything at once. The fact that your symptoms started around the same mileage gives me some peace of mind that it's probably not something more serious. Really appreciate you taking the time to share your experience. I'll update you once I get it sorted out, but I'm feeling much more confident now about what to expect. Looking forward to getting my Beemer running smoothly again!