BMW X7 Power Loss & Smoke: Knocking Engine Symptoms

Thanks for sharing your experience! Just had my latest service a month ago and currently at 49932 KM. I've always used premium fuel actually, but these symptoms only started showing up last week. I typically drive longer distances and let the engine warm up properly. The symptoms you described with your X5 sound spot on with what I'm experiencing. Good to know about the carbon deposit solution, that's actually quite reassuring and a more straightforward fix than I feared. Did you notice any gradual decline in performance before the issues became obvious, or did it just hit suddenly like mine?

Thanks so much for all the detailed info! It's super helpful to hear that your issue came on suddenly too, makes me feel better knowing I haven't been missing warning signs. I've already called my mechanic and booked an appointment for tomorrow morning. I mentioned the carbon deposit possibility based on your experience, and they agreed it sounds like a likely culprit. I'll definitely make sure they run a full diagnostic first, just to be on the safe side. The 425 euro cost you mentioned isn't too bad either, I was worried it might be something way more expensive! I'll update you once I get it checked out. Really appreciate you taking the time to share your experience, it's made me feel a lot more confident about getting this sorted. Thanks again!