Viper1000

2 months now

wootloops

Funny I was just posting about this in another thread. I had a stumble below 4000 RPM in my cayman S (3.4 DFI engine same as the 991 base). Replaced a bunch of parts but the only thing that fixed it was walnut blasting the intake valves. My car had 105k miles (so similar to OP of this thread) and they were covered in carbon deposits. Once I cleaned them up the car runs way smoother now throughout the rev range and feels like it makes slightly more peak power. I think it's worst at low RPMs because there isn't as much airflow and the variocam may not be opening the valves as much until high RPMs.

If anyone is having this issue with more than say 50k miles on the car this is what I would look into.

Bluey

Very interesting! Can you link your other thread where you discussed this?

Did you experience multiple blips/jerks in power during acceleration at low rpm and low speeds or just one at a specific rpm?

wootloops

I'd say it felt like maybe 2-3 jerks if I was at moderate throttle below 4k rpm. Once it got above 4k or so the car would pull fairly smooth, especially at wide open throttle.

Pretty in-depth discussion on this planet 9 thread, includes before/after pics of the valves: https://www.planet-9.com/threads/wal...-ports.251094/

I used an AUTOOL walnut blaster, and borrowed a large air compressor from a friend.