BMW M3 Rough Running: Common Causes & Repair Guide

I experienced similar issues with my 2008 BMW M5 last year. The symptoms were almost identical, rough idle, stalling, and jerking during acceleration. After inspection, it turned out to be a faulty ignition coil pack and worn spark plug connections. The wiring harness connecting to the coils had deteriorated, causing intermittent connection issues. The repair involved replacing all ignition coils, spark plugs, and the associated wiring harness. It was a serious issue that needed immediate attention since it could lead to catalytic converter damage if left unfixed. Based on your symptoms, I'd suggest checking the ignition system first, particularly the coil packs and their connections, before assuming it's a fuel pressure sensor issue. These symptoms are pretty common in BMWs of that era when the ignition system starts failing. Not a huge job for an experienced mechanic, but definitely not something you'd want to ignore.

Thanks a lot for sharing your experience with the M5! It really helps to hear from someone who dealt with similar issues. I actually took it to another shop yesterday and they also mentioned the ignition system might be the culprit. Would you mind sharing how much you ended up paying for the whole repair? Also curious if you've had any other issues pop up since getting it fixed? I'd love to be prepared for what might come next.

Hey there! Thanks for following up. Actually, while my M5 had similar symptoms, it turned out my initial suspicion about the fuel pressure sensor was spot on! I just had it fixed last week, they found a bad cable connection that was causing the sensor to act up. Only cost me 95 € to repair, which was a huge relief since I was worried it might be something more serious like the ignition system problems I mentioned before. Since getting the fuel pressure sensor sorted, my car's running like a dream, no more rough idling, stalling, or jerking during acceleration. The check engine light's gone too. Honestly, I'm pretty relieved it wasn't the ignition system after all, as that would've been a much bigger job. Just a heads up though, make sure they check all the connections thoroughly. Sometimes these issues can be as simple as a loose or corroded connection rather than a completely failed component. Hope you get yours sorted soon! Let us know how it goes.

Thanks for the update! Just got back from my mechanic today and wanted to share what happened. Turns out it was actually the fuel injectors that were causing all the trouble. They were pretty clogged up and needed a thorough cleaning. The whole job, including diagnostics and labor, cost me about 300 bucks, not too bad considering I was worried it might be something way more expensive! The mechanic I went to this time was much better than my previous one. They took the time to show me the dirty injectors and explained everything clearly. Car's running smooth now, no more jerking or stalling. What a relief! They also mentioned I should use better quality fuel to prevent this from happening again. Really appreciate everyone's input on this. Sometimes getting a second opinion (or third!) really makes all the difference. Lesson learned about sticking with a mechanic who knows what they're talking about and actually takes the time to explain things properly.