911 Turbo Troubles: Black Smoke & Power Loss Mystery

I experienced similar issues with my 2015 Porsche Cayman S last month. The symptoms you're describing sound very familiar, I had black smoke, power loss, and that distinctive whistling noise. Turned out to be more than just a sensor issue in my case. My ECU (engine control unit) was malfunctioning, causing incorrect fuel mixture and turbo pressure readings. Took it to the official Porsche service center, didn't want to risk it with independent shops given how complex these systems are. They ran a full diagnostic and found that the ECU needed replacement. It was pretty serious since the ECU controls basically everything in the engine management system. The repair took about three days including testing. If you're getting those symptoms, I'd strongly suggest going to a Porsche specialist or dealership. The ECU isn't something you want to take chances with, especially on a 991. Better to get it properly diagnosed than risk further engine damage. Hope this helps with your decision. Let us know what you find out.

Thanks a lot for sharing that! Really helpful to hear about your experience. Mine sounds exactly like what you went through. Hey, just wondering, do you remember roughly how much you ended up paying for the ECU replacement? Also, has everything been running smoothly since the fix, or have you noticed any other quirks?

Hey again! Yeah, happy to share the follow-up. The total bill came to €1000.0 for fixing the ECU, definitely not cheap, but worth every cent considering it's such a crucial component. The charge air temperature sensor malfunction that was causing all those nasty symptoms got sorted out in the process too. I'm really glad to report that since getting it fixed at the Porsche center, my Cayman's been running like an absolute dream, no more black smoke, weird noises, or power issues. It's back to being the beast it should be! The whistling noise completely disappeared, and the performance is spot on again. I reckon you should definitely get yours checked out at the official Porsche service center. They might be a bit pricier than independent shops, but they really know what they're doing with these cars. Plus, with issues like these, it's better to nip them in the before they cause any more expensive problems down the line. Let me know how you get on with yours, I'm curious to hear if it turns out to be the same issue!

Thanks so much for all the detailed info! Just wanted to update you on what happened with my 991. Took your advice and went to the Porsche service center yesterday. You were spot on, it was indeed an ECU issue, but I also had a failing turbo sensor that needed replacing. Bill came to about €1,200 total, which was actually better than I expected after reading your experience. The best part? My car's running perfectly now! No more black smoke, the weird whistling's gone, and the power's back to normal. Feels like I'm driving a new car again. Really glad I didn't try to cheap out with a unusual mechanic. Thanks again for your help, you probably saved me from making a costly mistake by going to some unusual shop. Definitely keeping the Porsche center as my go-to from now on. Sometimes you just have to bite the bullet and pay a bit more for quality service, right? Cheers for all the help!