BMW 4 Diesel Troubles: Idle Issues & Power Loss Help

Hey there! I had a similar issue with my 2020 BMW 3 diesel. I've got some experience working on cars, mainly basic maintenance stuff. When my engine started acting up just like yours, rough idle, poor acceleration, and that dreaded check engine light, I took it to my regular workshop. They diagnosed a faulty DISA valve, and the symptoms matched exactly what you're describing. The complete DISA unit had to be replaced, cost me around 280 Euro, but it fixed the problem completely. The car runs smooth as silk now. Before I share more specific details about my repair experience, what's your exact engine type and mileage? Also, are you getting any specific error codes? This info would help me tell you if you're dealing with the same issue I had.

Thanks for sharing your experience! Yeah, my car's at 121638 KM and just had its service last month. Those symptoms you described sound spot on to what I'm experiencing. Interesting to hear the DISA valve was the culprit in your case, that's really helpful to know. I've been worried about potential repair costs, so knowing what you paid gives me a good reference point. Haven't pulled any error codes yet, but planning to get that checked tomorrow. Your experience definitely makes me feel better about this whole situation. Really appreciate you taking the time to help out!

Hey again! Good to hear back from you. Yeah, after dealing with my DISA valve issue last year, I can say the symptoms you're experiencing are really similar to what I went through. My BMW was also around that mileage mark when it happened. Just wanted to add, after I got mine fixed, I learned these valves typically start acting up around 100,000-130,000 KM, so your timing fits the pattern. Getting those error codes checked is definitely the right move, that's exactly what I should've done sooner. I actually waited a couple weeks before getting mine checked, and honestly, that wasn't smart because the rough running can potentially affect other components. One thing I forgot to mention in my first reply, when my mechanic replaced the DISA valve, they recommended checking the intake manifold seals too. Turns out they were a bit worn, and replacing those along with the DISA valve made a huge difference in how the car runs. Might be worth asking about when you get yours checked. Let me know what those error codes show up. Would be interesting to see if they match what I had (P1017 and P1018 in my case). Good luck with the diagnosis!

Thanks so much for all that detailed info! That's really good to know about the typical mileage range for DISA valve issues, makes total sense why mine's acting up now. I'll definitely ask about those intake manifold seals when I take it in, hadn't even thought about that. Don't want to risk causing more problems by waiting too long. Honestly, you've been super helpful with sharing your experience. I've written down those error codes you mentioned (P1017 and P1018) to compare with whatever shows up on my diagnostic tomorrow. Will probably go ahead and get both the valve and seals checked since I'm already taking it in. Better to handle everything at once than keep making separate trips to the shop. Thanks again for taking the time to help me figure this out, really appreciate all the advice!