BMW M3 Rough Running + Failed Emissions, Help Needed

Hey there! I faced almost identical issues with my 2013 BMW M4 last year. The symptoms you're describing match exactly what I experienced, rough idle, power loss, and constant CEL. My car would also jerk during acceleration, especially between 2000-3000 RPM. Turned out to be a failing fuel injector. Had this diagnosed at my local BMW specialist after my regular mechanic couldn't pinpoint the issue. The defective injector wasn't atomizing fuel properly, causing uneven combustion and rough running. They found cylinder 4 injector was the culprit after running proper diagnostics. They had to replace the faulty injector and calibrate the new one. While it was a serious repair that took a couple of days to complete (parts weren't immediately available), it wasn't catastrophic to the engine since I caught it early. Just don't wait too long, bad injectors can cause additional damage if left unchecked. If you're experiencing similar symptoms, I'd strongly suggest getting it checked at a shop that specializes in BMW performance vehicles. These engines are quite sophisticated and need someone who really knows what they're doing. Hope this helps.

Hey, thanks for sharing your experience! That's really helpful since it sounds exactly like what I'm dealing with. Good to know I'm not alone with these symptoms. My mechanic actually mentioned it might be the injectors too, but I wanted to get some real-world feedback before committing to the repair. Quick question, do you remember roughly how much you ended up paying for the whole job? And has everything been running smoothly since the repair, or have you noticed any other issues pop up?

Hey again! Happy to give you an update! I had the repair done and can confirm it sorted out all those mixture preparation problems I mentioned before. The total bill came to 515 € for replacing the defective injection valve/injector. Honestly, looking back, it was worth every penny. My M4's been running like a dream since the fix, no more jerking, stalling, or power issues. The engine's smooth as silk now, and that annoying check engine light hasn't come back. It's like having a completely different car! Best part is, I haven't had a single related issue pop up since the repair. Just regular maintenance stuff. If you're still on the fence about getting it fixed, I'd say go for it. These symptoms won't fix themselves, and waiting could just lead to bigger problems down the road. The peace of mind alone was worth the investment. Let me know if you need any other info about the repair process!

Thanks for the detailed feedback! I wanted to let you know I finally bit the bullet and took my M3 to the mechanic yesterday. Turns out you were spot on, it was indeed the fuel injectors causing all those issues. Had them replaced and wow, what a difference! The whole job set me back about 600 bucks, which wasn't as bad as I was expecting. They found that two injectors were actually failing, but managed to get it all sorted in just one day. The mechanic walked me through everything they did and even showed me the old parts. Took it for a test drive after, and it's like having a completely new car. No more jerking, stalling, or power loss. The engine's running super smooth now, and that pesky check engine light is finally gone. Really glad I didn't wait any longer to get it fixed. Thanks again for sharing your experience, it really helped me make the decision to get it sorted!