BMW M3 Engine Jerking and Power Loss, Need Help

Hey there! I have some experience working on BMWs, and I actually faced a similar issue with my 2016 BMW M4 last year. The symptoms you're describing sound very familiar. My car was also jerking and losing power, turned out it was due to a sketchy third-party tune I had installed. Had to take it to a specialist workshop who reset the ECU and reinstalled the factory settings. The whole fix, including diagnostic work, cost me around 180 Euro but it solved the problem completely. Before I can give you more specific advice, could you tell me if you've had any recent modifications or tuning done to your M3? Also, what's the exact fault code you're getting? This would help narrow down if we're dealing with the same issue.

Thanks for your response! Just to clarify, my M3 is completely stock with no modifications or tunes. I should have mentioned earlier that my fault code is P0300 (unusual/multiple cylinder misfire detected). The issue started about a week after my latest service. Currently at 150468 KM, and I've always kept up with regular maintenance at authorized dealers. It's quite frustrating as the car runs perfectly fine sometimes, but then suddenly starts acting up during highway cruising. Could it be something simpler like spark plugs or coils?

Hey again! Thanks for providing those extra details about your M3. You know what? That P0300 code actually rings a bell, had the exact same thing happen with my M4 about six months after what you're experiencing now. Initially thought it was my tune causing issues, but after you mentioned yours is stock, I remembered my second encounter with this problem. In my case, it turned out to be a combination of worn spark plugs and one bad ignition coil on cylinder 4. These BMWs can be quite sensitive to aging ignition components. Since you mentioned it started after your service, and considering your mileage, I'd bet money it's the same issue. My symptoms were identical, unusual jerking, especially during steady highway cruising, and that frustrating intermittent behavior where sometimes it runs perfectly fine. Got all my spark plugs replaced and that one bad coil, problem solved completely. Cost me way less than my previous ECU reset adventure, and the car's been running smooth as butter since then. Would definitely suggest checking those components first before diving into anything more complex. Mind if I ask, when was the last time you had your spark plugs changed? Our M engines can be pretty hard on ignition components, especially when they get some miles on them.

Thanks a lot for sharing your experience! You just described my symptoms exactly, especially that intermittent behavior that's been driving me crazy. Come to think of it, I can't actually remember when the spark plugs were last changed, I'd have to check my service records. Might have been overdue for a replacement without realizing it. I really appreciate you pointing me in this direction. It makes total sense, and I'm actually relieved it might be something relatively straightforward rather than a major engine issue. I'll get those spark plugs and coils checked right away. Will definitely get them all replaced if that's what's needed, rather do them all at once than have to deal with this problem again soon. You've been super helpful! I'll update once I get it sorted. Hoping for that same "smooth as butter" result you got with yours!