Panamera Diesel's Power Loss & Hissing Mystery Solved

Had the exact same symptoms on my 2015 Cayenne Diesel last year. The rough idle, power loss, and hissing were spot-on identical to what you're describing. Turned out to be a broken swirl flap in my case, one had actually come loose and was rattling around in the intake manifold. Took it to my trusted Porsche specialist mechanic because it's definitely not a DIY job. The whole intake manifold had to come off to fix it. They found metal debris from the broken flap had started circulating, which could've caused some serious engine damage if left unchecked. The repair took about two days, and yes, it was a serious issue that needed immediate attention. Would've risked major engine damage if I'd kept driving it. My advice? Get it checked ASAP at a proper Porsche specialist, this isn't something you want a regular garage messing with.

Thanks for sharing your experience, it's super helpful to hear someone had the same issue! Your symptoms match mine exactly, and I'm relieved to know there's a clear fix. Quick question, do you remember roughly how much the repair set you back? Also, has everything been running smoothly since the fix, or have you noticed any other issues pop up?

Hey again! Happy to help update you on the costs and results. Yeah, the whole repair ended up costing me 865€ at my Porsche specialist. Bit of a hit to the wallet, but honestly, it was worth every penny because the car's been running like a dream since then. The Swirl flap control error got completely sorted out, and all those scary symptoms, the hissing, rough idle, power loss, they're all gone. It's been over a year now since I had it fixed, and I haven't had a single issue pop up related to that problem. The engine runs super smooth, no more jerking during acceleration, and that annoying check engine light hasn't come back on. My Cayenne feels like new again! Just make sure you get it fixed soon, those metal bits floating around in the intake manifold can cause some serious damage if you leave it too long. Trust me, you'll feel the difference as soon as it's fixed! Let me know how it goes when you get yours sorted!

Thanks so much for all the details! I actually just got back from the mechanic today. You were absolutely right, it was the swirl flap issue. I found a really good Porsche specialist through a 's recommendation, and they sorted it out in about two days. The repair cost me around 900 €, pretty close to what you paid. I was nervous at first, but what a difference! The car drives like new again, no more hissing, shaking, or power loss. It's amazing how smooth everything feels now. Honestly, I'm just relieved I caught it when I did. The mechanic showed me the broken flap and some of the metal debris they found, pretty scary stuff! They said I made the right call bringing it in when I did. Really appreciate your help in identifying the problem. Saved me from stressing out too much about it. Now I've got a trustworthy Porsche specialist for future repairs too, so that's a bonus! Thanks again for your advice, it really helped me make the right decision!