BMW Diesel's Mystery: Stalling, Jerking, and Whistling

Hey there! I had nearly identical issues with my 2016 BMW 3 Series 320d. That whistling sound combined with power loss is quite familiar. Last month, I took it to the garage after experiencing similar symptoms, rough idle, jerky acceleration, and that distinctive hissing noise. Turned out my boost pressure sensor wasn't the culprit. The technician found a damaged wiring harness connecting to the turbo actuator, plus a cracked vacuum hose. These issues were causing boost leaks and sending wrong signals to the ECU. The engine was basically running in limp mode to protect itself. The repair involved replacing the wiring harness and vacuum lines. Not a cheap fix, but definitely less severe than a full turbo replacement, which I initially feared. The car's running smooth now, back to its usual self with proper power delivery. Given your symptoms, I'd suggest getting a second opinion from another BMW specialist. These issues can snowball if left unchecked. Best of luck!

Thanks for sharing your experience! That seems very similar to what I went through. I'm glad you got it sorted out, electrical issues can be really tricky to diagnose. Just curious, do you remember roughly how much the repairs set you back? Also, has everything been running smoothly since the fix, or have you noticed any other quirks?

Hey again! Great to hear back from you. Actually, I just got my car back from a different mechanic last week, and I'm happy to report it was exactly what I suspected, a faulty boost pressure sensor. Much simpler than my previous wiring harness issue! The fix was pretty straightforward and only cost me 95 €, just needed to repair a dodgy cable connection to the sensor. Way cheaper than what I paid for that earlier harness problem I mentioned before. The car's running like a dream now! No more annoying whistling sounds, power's back to normal, and fuel consumption's returned to what it should be. The engine idles perfectly too, such a relief after all that drama. Really glad I decided to get that second opinion from another mechanic. Honestly, these BMWs are fantastic when they're running right, aren't they? Just need to stay on top of these little issues before they turn into bigger problems. Let me know if you need any other info, always happy to share what I've learned from my experiences!

Thanks for the update! Really appreciate you sharing the details. You're right, I decided to bite the bullet and took my car to a different mechanic yesterday. Turns out it was actually a split intercooler hose causing all the trouble, pretty common issue apparently. Got it replaced for about 150 bucks including labor. The mechanic was great, actually showed me the damaged part and explained everything clearly. What a difference from my last experience! The car's running perfectly now, no more jerking or weird noises, and the engine light's finally off. Fuel consumption's back to normal too. Can't believe I was stressing so much about it. Sometimes you just need to find the right mechanic to fix these things. Really glad I asked here and got your advice about getting a second opinion. These BMWs are definitely worth the occasional headache when they're running smoothly!