X7 Vacuum Leak Symptoms: Owner Needs Urgent Diagnosis

Had the exact same symptoms on my 2017 BMW X5 40i last month. The hissing sound and rough idle were identical to what you're describing. Took it to the garage and they found a split in the intake hose right after the MAF sensor. The rubber had deteriorated and created a significant vacuum leak. The symptoms match perfectly, rough idle, poor acceleration, and worse fuel consumption all happen because the engine's getting unmetered air. It's not a major issue if fixed promptly, but running it too long can cause the engine to run lean and potentially damage other components. The repair was straightforward, just needed a new intake hose and some clamps. Quick tip: you can try spraying some brake cleaner around the intake area while it's idling. If the engine note changes when you spray a particular spot, that's likely where your leak is. But given the symptoms, definitely get it checked soon. Just my take based on recent experience, but it sounds very similar to what I dealt with.

Thanks for sharing your experience! This definitely sounds similar to what I had. I'm going to check those intake hoses first thing tomorrow. Did you remember roughly how much the repair set you back? Also curious if you've had any other issues pop up since getting it fixed? My dealer quoted me an arm and a leg, so I'm trying to figure out if I should look for an independent shop instead.

Hey there! Glad I could help point you in the right direction. Just wanted to follow up, you'll be happy to know that after I got mine fixed, all those annoying symptoms completely disappeared. The repair was actually pretty reasonable, only cost me 100 € for replacing the leaking intake hose. My car's been running like a dream since then, no more hissing, rough idle is gone, and fuel economy is back to normal. I'd definitely recommend looking for a good independent shop rather than the dealer. Mine's been purring like a kitten since the fix, and I haven't had a single issue pop up afterward. Just make sure whoever you choose knows their way around BMWs. The air intake system leak seems scary at first, but it's actually a pretty straightforward fix once you find the right mechanic. Let me know how it goes with yours, always happy to share more about my experience if you need it!

Thanks for the update and the cost info! Just wanted to let you know what happened with my X7. I actually took your advice and found a reputable independent shop. Turns out you were spot on, they found a torn intake hose and fixed it right up. Only paid 150 € for parts and labor, way less than what the dealer wanted. The mechanic even showed me the split in the old hose. Got it back yesterday and what a difference! No more hissing, engine's running smooth as butter, and the check engine light's gone. Fuel gauge isn't dropping like a rock anymore either. Such a relief it wasn't anything major. The new mechanic seemed really knowledgeable about BMWs too, so I think I've found my go-to shop. Really appreciate you sharing your experience, saved me a lot of worry and money. Sometimes it's just nice to hear from someone who's been through the same thing.