BMW X7 Diesel Power Loss: Intake Manifold Mystery

I had almost identical issues with my 2020 BMW X5 30d last month. The symptoms were spot-on with what you're describing, power loss, rough running, and that distinctive hissing. The intake manifold control switch was definitely faulty, causing those flaps to malfunction. Had it fixed at the garage and it needed a complete manifold assembly replacement. The flaps were stuck, causing incorrect air distribution and messing with the fuel mixture. It was quite a serious issue that needed immediate attention since it was affecting engine performance and could've led to more damage. The repair took about 5 hours. They also cleaned the EGR valve while they were at it since they had to remove it anyway. After the fix, the engine ran smooth as new, fuel consumption went back to normal, and that annoying hissing disappeared completely. Don't put this repair off, the symptoms will only get worse and could potentially cause more expensive damage to other engine components.

Thanks for sharing that info about your X5! That's really helpful since it sounds exactly like what I'm dealing with. My symptoms match yours perfectly. Good to know it was fixable and your car's running well now. Would you mind telling me what the damage was to your wallet? Also, any other issues pop up since the repair? Just want to make sure I'm prepared for what's coming.

Hey again! Following up on my X5 repair, totally glad I could help! Yeah, the whole thing set me back 465 € for fixing that faulty intake manifold control switch, but honestly, it was worth every penny. My ride's been running like a dream since the fix about six weeks ago, no more hissing, power's back to normal, and fuel consumption is exactly where it should be. Haven't had a single problem since the repair job. The mechanic really knew their stuff and fixed it right the first time. The difference in how the car runs now compared to before is like night and day. You know that annoying rough running and power loss we talked about? Completely gone. Seriously, get it sorted sooner rather than later, your symptoms are identical to what I dealt with, and putting it off will just cause more headaches down the road. Trust me, you'll feel the difference right away once it's fixed!

Thanks so much for the detailed follow-up! After reading about your experience, I bit the bullet and took my X7 to a different mechanic yesterday. You wouldn't believe it, exact same diagnosis as yours! The intake manifold control switch was shot. The repair took about 6 hours, and while it wasn't cheap, the car's running amazingly now. No more hissing, the power's back, and the engine feels smooth again. Such a relief! The mechanic was really thorough and even showed me the faulty parts. Really glad I asked here before going ahead with the repair. Your experience gave me the confidence to get it sorted quickly instead of waiting around and potentially causing more damage. Thanks again for all your help, you saved me from a lot more stress and probably a bigger repair bill down the line!