Hoping there's a similar 997.1 4S war story out there to help me diagnose what's going on. Any help is majorly appreciated:

Currently my '06 C4S feels like it's hitting the rev limiter at about 3000 rpm under light throttle. I didn't hear any significant change in engine characteristics when this started, but I limped her home 1.5 miles at 40mph and then heard a low-volume squealing in my garage at idle.

I had been driving about 75mph for 2 hours from Vancouver to Seattle. I shut the car down for a 30 min ferry ride, then started her back up and got into slow moving traffic for about 4 miles, average speed 15mph.
Car started 'bumping' while pulling away from the last stoplight from my house. Upshifting would cease the 'bumping' until about 3000 RPM, essentially giving me about a 1200 RPM band to work with.

Any ideas? Would really like some help here.

Thanks.

 

If car does not show any CELs and behaves like it hits rev limiteer at 3K rpm - PIWIS diagnostics is required. Means dealer or good local shop with PIWIS machine.

 

Thanks for the feedback, noted. Anyone experienced this or have other ideas?

 

Also, I forgot to mention that I have the Durametric OBD software, but I don't really know what values I should be looking at. Input on that appreciated as well.
Thanks.

 

sounds like bad coils

 

Perhaps the power to the coils is limited. More ignitions per second could require more energy than being supplied to the coils if the connection to the coils is not good.

 

Hmm, it could be the coils. Just use your Durametric and check for any fault codes. It just might tell you something.

 

Ran Durametric and cleared a couple of old misfire codes. No *new* codes were populated in the home screen (no check engine light either), but then I ran the real-time DME tool and saw that cyl 1 was misfiring at initial idle until the engine settled down to 780 RPM. In total there were 28 misfires of the #1 until the 780 idle. Any idea if this is normal?

Appreciate all the input, 6ers!

 

Hmmm, could it also be a stuck lifter in cylinder#1? I think you may have to take this to the shop.

 

Yeah, I think the shop is inevitable on this one. Maybe I'll use the "opportunity" to roll up my sleeves with the Durametric and learn to analyze some of the parameters. Thanks for the input.

 

This may help in learning of the Durametric :

https://www.6speedonline.com/forums/...-software.html

 

Bad tank of gas ? Almost sounds like some type of clogging .
Just guessing.

 

I have had something similar happen twice when the gas tank got below a 1/4. Now I just make sure to fill her up at the 1/4 mark and no problems.

 

my durametric shows same on cylinders 6 and 3, i think it is software glitch. any misfire at any RPM must generate CEL code.

 

fuel pump and clog in fuel line - very possible thing, if there is no enough fuel, but it is such a rare thing for high pressure fuel pumps... who knows.