BMW M3 Rough Running & Stalling Mystery Needs Help

I had nearly identical issues with my 2012 BMW M5 last year. The symptoms were spot on with what you're describing, rough idle, increased fuel consumption, and poor acceleration response. My check engine light was also illuminated. After diagnostic testing at the garage, it turned out the mass airflow sensor was indeed faulty. The mechanic showed me the sensor was contaminated and giving incorrect readings to the ECU. The repair involved replacing the MAF sensor and cleaning the surrounding housing. It wasn't a complex fix, but it was crucial since the MAF directly affects the air-fuel mixture. The repair solved all the issues, the engine ran smooth again, fuel economy returned to normal, and the stalling stopped. While not the most severe problem, leaving it unfixed could've led to catalytic converter damage due to improper fuel mixture. If your symptoms match these, I'd definitely get the MAF sensor checked out.

Thanks for sharing your experience! That's really helpful as it sounds exactly like what I'm dealing with. I'm relieved to hear it wasn't something more serious. Would you mind telling me roughly how much you ended up paying for the whole repair? Also, has everything been running smoothly since then, or have you noticed any other issues pop up? I'm trying to budget for this and want to make sure I'm prepared if there might be related problems down the line.

Hey there! Happy to share an update. I actually just got my M5 fixed last week, the mass air flow sensor was indeed the culprit, just as I suspected. The total bill came to 365 € for the replacement and labor, which honestly wasn't as bad as I feared it might be. Since the repair, my car's been running like a dream! The idle is super smooth now, acceleration is crisp again, and my fuel consumption is back to normal. It's like having a different car, in a good way! The mechanic did a thorough job cleaning the housing too, which probably helped. I haven't noticed any other issues popping up, and it's been a solid week of daily driving. My advice would be to just focus on getting the MAF sensor sorted first, it really sounds like that's your main issue given how similar your symptoms are to what I experienced. Trust me, you'll notice the difference right away once it's fixed. The price I paid seems pretty standard for this kind of repair on our type of car, so it should give you a good idea for budgeting. Just make sure you go to a shop that knows their way around BMWs, it makes a difference!

That's such a relief to hear! I actually just got back from the mechanic and you won't believe it, it was exactly what you described! The total cost was a bit more than what you paid, but honestly, I'm just happy it's fixed. They showed me the old MAF sensor and wow, it was pretty dirty. Took it for a test drive after the repair and what a difference! The engine's purring like it should, no more stalling, and it feels so much more responsive. Really glad I asked here before going in, helped me feel more confident about the diagnosis and what to expect. The mechanic mentioned regular air filter maintenance might help prevent this issue in the future, so that's definitely something I'll keep an eye on. Thanks again for sharing your experience, saved me a lot of worry and helped me make an informed decision. Time to enjoy my smooth-running M3 again!

High Charge Pressure Deviation charge pressure control

(Translated from German)

If you're experiencing a high charge pressure deviation, it could be related to issues with the turbocharger system. Start by checking for any vacuum leaks or damaged hoses connected to the turbocharger. Also, inspect the wastegate actuator and ensure it's functioning properly. If the problem persists, it might be best to have a professional mechanic take a closer look, as turbocharger issues can affect engine performance and efficiency. Let me know how it goes or if you have any further questions!