BMW M3 Idle Problems: Control Valve or Something Else?

Hey there! I had a pretty similar issue with my 2020 BMW M4 last year (I'd say I have some experience working on BMWs and also owned an M2 before). The symptoms you're describing sound exactly like what I went through. After scanning it, my workshop found that the intake was heavily contaminated, which was messing with the air-fuel mixture. Got it cleaned professionally and they also checked the sensors, total bill came to around 425 Euro, but it's been running smooth as butter since then. Could you share more details about when these symptoms started and if you've noticed any performance changes when accelerating? This would help me understand if you're dealing with the same problem I had.

Thanks for sharing your experience! My M3 has 128351 KM on the clock, and these issues started showing up about two weeks after my latest service. Interesting you mention the intake, I've noticed a slight power drop during acceleration, especially in the mid-range. The stalling mostly happens when the engine's warm, and it's definitely more noticeable during slow-speed maneuvers. Think I'll get it checked out by a professional based on your experience. Did you notice any specific driving conditions that made your symptoms worse?

Yeah, tell me about it! When I had this issue with my M4, it was definitely worse when the engine was warm, just like you're experiencing. The symptoms would get really obvious during slow-speed parking or when I was stuck in traffic. What really caught my attention in your case is that it started after your service. You know, that's exactly when mine started acting up too. Makes me wonder if there might be something loose or not properly connected after the service work. In my case, besides the contaminated intake, they actually found a small vacuum leak that was contributing to the problem. The power drop you're mentioning in the mid-range, that's super familiar. Before I got mine fixed, it felt like the car was holding back, especially between 2000-4000 RPM. The stalling was definitely scarier though, especially when it happened at intersections. Given your mileage and symptoms, I'd bet you're dealing with something similar to what I had. My advice would be to get it checked soon, these symptoms tend to get worse over time. When I waited too long, the stalling started happening more frequently. Definitely have them look at the intake system and check for any vacuum leaks while they're at it. Let me know what you find out, I'm curious if it turns out to be the same issue!

Really appreciate the detailed info! You're right about the warm engine symptoms, it's worst when I'm crawling in traffic. The RPM starts dancing between 600-1000, and sometimes it just dies on me. That similarity with your experience, especially about it starting after service, is making me pretty nervous. I've already called my mechanic and booked it in for next week. The vacuum leak angle is something I hadn't considered. Makes total sense though, especially with that power drop I'm feeling. It's exactly as you described, that hesitation between 2000-4000 RPM is spot on. I was focused on the idle control valve, but now I'm thinking it could be intake-related like your case. Thanks again for sharing your experience, definitely helped me narrow down what to look for. I'll update you once I get it checked out. Hopefully it'll be a straightforward fix like yours was!