Car won't rev. over 5000 RPM

[GT-Racer]

My 996 won't rev over ~5000 RPM. It's acting similar to the rev limiter but at lower RPM. It occurs under load at any gear, or unloaded when reving in neutral. The car misfires and shakes if I continue accelerating, but even if I floor the pedal to the ground the RPMs stay right below 5000 RPM.

This happened when I picked up my car at the dealer after I asked them to put a new race clutch disk and a re-enforced pressure plate from Sacks. I already had a light flywheel from AASCO Motorsports, but had to replace the insert. Clutch Masters took care of replacing the insert and test the complete set up before sending everything to the dealer.

The dealer Porsche at Stevens Creek in San Jose didn't do much, they blamed everything on my ECU and the fact that that my car is heavily modified. They just checked the gearbox and since they couldn’t figure it out, they told me to pick up my car and go. The fact still remains that my engine did not run like that when I dropped it off.

I did some homework on my own - I swapped ECUs, MAF sensors, checked air intake, multi-plugs, O2 sensors, and wiring harness, but nothing changed.

I also checked a few websites and realized that the speed sensor could be misplaced or damaged, but I am not sure that would cause the symptoms I have described (my car still runs). I also read that I may have a bent flywheel tooth (the light flywheel was shipped to and back from LA and could have been damaged during transportation).

Bottom line, I don’t understand what could have happened. Any suggestions?

Thanks for the help!!

[Loren]

I would have them test the RPM crankshaft position sensor.

[GT-Racer]

Loren, thanks a lot for your quick reply. I was wondering - is the speed sensor the same as the one you are suggesting? Where is it located? Thanks again!

[JimB]

What year is your car? If you have a 3.6L I would bet its a problem with the variable valve lift. I had the exact symptoms when we swaped a 3.6L into a 99 and the valves were not switching properly.

[GT-Racer]

I brought my car to another dealer (Porsche Rector) and they found and fixed the problem right away. A bent tooth on the flywheel was creating the problem - the speed sensor was not reading properly and sending the wrong reading to the ECU – Kudos to Rector, their head mechanic, and outstanding service team. Porsche Stevens Creek really did a poor job. In fact, the shop foreman was rude and showed such a lack of experience and respect by telling me that I brought my car in that way. Not only could they not fix my car, they damaged/scratched my paint by the passenger door and splitter. Obviously, I am going to contact the factory and let them know the treatment I received after so many years of loyalty and multiple referrals. I guess things change…

Loren, Jim, thanks again for your support and suggestions.

[c4bliss]

Luis,

You going to Santana this weeknd?

If so, see you there!