Porsche 996: Hissing Engine & Power Loss Mystery Solved

Hey there! I have some experience with cars and had a very similar issue with my 2004 Porsche Boxster last year. The symptoms you're describing sound exactly like what I dealt with, especially that annoying hissing sound! Found out it was indeed a cracked intake hose that was causing all those problems. Took it to my regular workshop, and they spotted the leak pretty quickly. Parts and labor came to about 100€, and it fixed all those issues, no more jerking or power loss. Could you share what engine you've got in your 996? Might help me give you more specific advice based on my experience with these Porsches. Also, have you noticed any specific conditions when the symptoms get worse (like cold starts or hot weather)?

Thanks for sharing your experience! You might be onto something with that intake hose issue. My last service was just two months ago and everything was fine until these symptoms started showing up. I'm at 51199 KM and it's been running like a dream until now. The symptoms seem worse during cold starts, and the hissing gets really noticeable when I rev above 3000 RPM. I've got the 3.6L engine, and it's been super reliable until this started. Gonna get it checked out soon, but your input makes me feel better about it possibly being just a hose issue rather than something more serious! Fingers crossed it's as straightforward as yours was.

Hey again! Glad I could help ease your mind a bit. You know what's funny, my Boxster had almost the exact same mileage (around 52000 KM) when this happened to me. The fact that yours acts up more during cold starts and gets worse above 3000 RPM is super similar to what I experienced. Just to follow up on my previous repair, after they fixed that intake hose, it was like having a completely different car! The hissing disappeared instantly, and that annoying jerking during acceleration? Gone completely. My mechanic actually showed me the old hose afterward, had a nasty crack right where it connects to the throttle body. Since you've got the 3.6L (mine's the 2.7L in the Boxster), the repair might be a bit different, but the principle should be the same. One tip though, when you take it in, ask them to check all the surrounding hoses while they're at it. My mechanic did this and found another one that was starting to show wear. Better to catch these things early, right? Let us know how it goes! Pretty sure you'll be back to enjoying that sweet Porsche performance in no time. These engines are built like tanks, it's usually just the little things that need attention.

Thanks so much for all the detailed info! Really appreciate you taking the time to share your experience and those extra tips. I've actually just booked it in for tomorrow morning at my regular Porsche specialist, and I'll definitely ask them to check all the surrounding hoses like you suggested. Makes total sense to catch any potential issues while they're already in there. You've made me feel a lot more confident about this whole situation. The similar mileage thing is quite interesting too, maybe it's just that time in these cars' lives when these hoses need some attention. I'll update the thread once I get it sorted. Thanks again for your help!