BMW 4 Series Rough Running & Valvetronic Troubles?

Hey there! Had the exact same symptoms with my 2012 BMW 335i last summer. Initially thought it was something minor, but the diagnostic confirmed it was indeed a Valvetronic issue. The mechanism that controls the valve lift wasn't working properly, causing those exact symptoms you described, rough idle, hesitation during acceleration, and terrible fuel consumption. Took it to my trusted mechanic who specializes in German cars. The Valvetronic servo motor had failed and needed replacement. They also had to do a complete run-in procedure after installing the new parts to ensure everything was properly calibrated. It was definitely not a quick fix, had my car in the shop for about three days. It's not something you want to leave unattended as it can lead to more serious engine problems down the line. Make sure whoever works on it has experience with BMW Valvetronic systems and proper diagnostic equipment. The symptoms you're describing are textbook Valvetronic failure, and it needs proper attention. Just my two cents based on my experience.

Thanks for sharing that experience! Glad you got it sorted out. Would you mind telling me how much the whole repair ended up costing you? Also curious if you've had any other issues pop up since getting it fixed, hoping to get an idea of what I might be looking at here. Been really stressed about this whole situation, so any extra info would be super helpful!

Hey again! Happy to report that since getting the Valvetronic issue fixed, my car's been running like a dream! The total bill came to 575 € for the whole repair job, that covered both the parts and labor, including that essential run-in procedure I mentioned before. Honestly, while it wasn't cheap, it was totally worth it considering how smoothly everything's working now. The best part? Haven't had a single related issue since the repair. The rough idle completely disappeared, acceleration is smooth again, and my fuel consumption is back to normal. My mechanic really knew what they were doing with these Valvetronic systems, made all the difference. Don't stress too much about it. Once it's properly fixed, these systems are actually quite reliable. Just make sure you get someone who really knows BMWs to do the work. Trust me, I know exactly how you're feeling right now, but there's definitely light at the end of the tunnel! Let me know if you need any other info, happy to help!

Thanks so much for all that detailed info! I actually went ahead and got my car fixed last week, and I wanted to update everyone here. Turns out you were spot on, it was definitely the Valvetronic system. Found a really good mechanic who specializes in BMWs, and they sorted everything out. The final bill was a bit higher than yours, around 650 €, but they also found and fixed a few minor issues while they were at it. The best part is how the car's running now, it's like night and day! No more stuttering, the engine's super smooth, and I'm not bleeding money on fuel anymore. The mechanic did a fantastic job explaining everything they were doing, which made me feel a lot better about the whole situation. They even showed me the old parts and explained why they failed. Really appreciate everyone's help and advice here. Sometimes it's just good to know you're not alone dealing with these car troubles! And yeah, you're right, having the right mechanic really does make all the difference. Thanks again for sharing your experience, it really helped me make the right decision!