M4 Fuel Injection Woes: Smoke, Stalls, and Solutions Needed

Hey there! I actually had very similar issues with my 2020 BMW M5 last year. The symptoms you're describing match exactly what I experienced, the jerking, increased fuel consumption, and those annoying stalls at idle. Took it to the shop and turned out it was indeed injection-related. The main issue was a faulty connector on one of the fuel injectors, the cable had developed a bad connection due to engine vibration. While it wasn't a catastrophic problem, it definitely needed immediate attention to prevent any serious engine damage. They had to replace the wiring harness for the injector system and recalibrate the fuel mapping. The repair wasn't particularly complex, but it needed specialized diagnostic equipment to pinpoint the exact issue. The smoke you're seeing is likely unburnt fuel from the faulty injection, mine did the same thing. My advice? Don't wait on this one. These symptoms won't resolve themselves and could lead to bigger problems. Look for a shop that specializes in BMW performance vehicles and has proper diagnostic tools for M series cars.

Thanks for sharing your experience with the M5! I went ahead and got mine fixed last week, and it's running much smoother now. Curious though, do you remember roughly how much you ended up paying for the repairs? Also, has everything been running smoothly since then, or have you noticed any other issues pop up?

Hey again! Great to hear you got your M4 sorted out! Since you asked, my repair bill came to 95 € for fixing the cable connection issue with the injector, pretty reasonable considering what could've gone wrong if left untreated. The mechanic did a fantastic job diagnosing and repairing the injection system fault. And you'll be happy to know that since getting it fixed, my M5 has been running like an absolute dream. No more jerking, no unusual stalls, and fuel consumption is back to normal. It's been over a year now and I haven't had a single injection-related issue pop up. The smoke during acceleration completely disappeared too. Just keep up with regular maintenance and you should be good to go. These M series engines are pretty solid once you sort out any minor issues. How's your fuel consumption now after the fix? Bet you're noticing a big difference!

Thanks so much for asking about my repair experience! Just wanted to update that I finally got my M4 back from the mechanic yesterday. Talk about a wild ride! Found a specialist who really knew their stuff, super thorough with the diagnostics. Turns out it wasn't just the injection system, they also spotted a loose connection in the wiring harness that needed fixing. Total bill came to about 800 bucks, which honestly wasn't as bad as I feared. The whole experience was way better than my previous mechanic drama. Shop was clean, they explained everything clearly, and even showed me the faulty parts. Car's running like new now, no more jerking or stalling, fuel consumption's back to normal, and that annoying smoke is completely gone. Such a relief! Actually took it for a proper drive this morning and it felt like I was driving it off the showroom floor again. Definitely learned my lesson about not waiting too long when these issues pop up. Thanks again for pushing me to get it checked out promptly. Really helped prevent what could've been a much bigger headache!