Porsche 991 Spewing Black Smoke: EGR System Crisis?

Hey there! I had a somewhat similar issue with my 2016 Porsche Cayman (I have some experience working on cars). The symptoms you're describing sound familiar, I also had black smoke and power loss. Turned out it was damaged cables on the electric changeover valve. Took it to my regular workshop, and they diagnosed it pretty quickly. Cost me around 155 Euro to fix, and it's been running smoothly since then. But before I jump to conclusions, could you share more details? Like: Have you scanned for error codes? When exactly did this start happening? Does it happen only during hard acceleration or all the time? This might help pinpoint if you're dealing with the same issue I had or something else entirely. Porsches can be tricky, so it's worth getting all the details right!

Thanks for sharing your experience! Mine's at 15047 KM and had its latest service just two months ago. The issue started about a week ago, and yeah, I've got the codes scanned, showing P0401 and P0402. It's happening mostly during moderate to heavy acceleration, not so much during normal cruising. The smoke and power loss are particularly noticeable when I'm pushing it above 4000 RPM. Really hoping it's just a valve issue like yours and not something more serious. The Porsche specialist I usually go to is booked solid for the next two weeks, so I'm trying to gather as much info as possible before I take it in.

Hey again! Thanks for sharing those details, those error codes definitely sound like EGR-related issues, but probably not exactly what I had with my Cayman. The P0401 (insufficient EGR flow) and P0402 (excessive EGR flow) together are kind of interesting, could indicate the EGR valve itself might be sticking or not responding properly. While my issue with the changeover valve cables was similar in symptoms, yours sounds more specifically EGR-related than mine was. Since you mentioned it's particularly noticeable above 4000 RPM, that's actually a bit different from what I experienced, my issues were more consistent across all RPM ranges. Quick question, have you noticed any changes in fuel consumption since this started? When I had my valve issue, I saw my fuel economy take a pretty significant hit before I got it fixed. I know waiting two weeks isn't ideal, but honestly, with these kinds of Porsche-specific issues, it's usually worth waiting for a specialist rather than going to a regular shop. While you're waiting, might be worth keeping the RPMs lower if you can, I learned that the hard way with my Cayman! Let me know how it goes when you get it checked out, always curious to learn more about these issues, especially since our cars are pretty similar!

Thanks so much for the detailed response! And yes, actually, I've noticed my fuel consumption has gone up by about 20% since this started. I've been babying it and keeping it under 3000 RPM for now, just to be safe. You're absolutely right about waiting for the specialist, I'd rather wait the two weeks than risk having someone less experienced work on it. The P0401 and P0402 codes together do seem a bit odd, which is making me nervous, but hopefully it's just the EGR valve acting up and nothing more serious. I'll definitely update everyone here once I get it diagnosed and fixed. Really appreciate all your help and sharing your experience with the Cayman, it's great to have this kind of community support when dealing with these issues!