Stutter from 6-7K RPM?

[supedgte]

I usually don't push my 996 hard but have opened her up probably 4-5 times. Over the weekend, I banged out 1st and 2nd gear and there was something different this time. From around 6-7K, the acceleration would start to break up a bit. Anyone have an idea what may be causing this? It's an 02 with 30K miles...Thanks!

[PAULSPEED]

Hi,

Sounds like bad gas.

Paul

[alstarz88]

I usually don't push my 996 hard but have opened her up probably 4-5 times. Over the weekend, I banged out 1st and 2nd gear and there was something different this time. From around 6-7K, the acceleration would start to break up a bit. Anyone have an idea what may be causing this? It's an 02 with 30K miles...Thanks!

have you checked the AFM

[JimB]

As I mentioned on Rennlist, I'd bet my grandmother that it's the cam timing switching. Try this. First accelerate slowly and see if it's worse. If it studders and gains rpms slowly and then catches. Second see if it varies or if it always happens at the same rpm.

[supedgte]

As I mentioned on Rennlist, I'd bet my grandmother that it's the cam timing switching. Try this. First accelerate slowly and see if it's worse. If it studders and gains rpms slowly and then catches. Second see if it varies or if it always happens at the same rpm.

Thanks for your insight on this Jim...I'll check in the next few days and post my results.

[Richard Hamilton]

Check the coil packs too.

[White987S]

I am going with bad gas too or a dirty fuel system. Are you running 93 octane? Run a few tanks with a high quality fuel cleaner with Techron like the Chevron product. Get the concetrated one that treats up to 20 gallons. They have a smaller one too, but it only treats 12 gallons.

[zegypt]

It could be bad gas, but this has happened to me as well for another reason and it was an easy fix. I just cleaned the throttle body (with carb cleaner) and the MAF (with non-residue electronics cleaner) and my 2002 C2 felt great with even throttle response throughout the power range with no fluttering. These are cheap maintenance items that should be done regardless....

http://www.renntech.org/forums/index.php?s...hl=maf++cleaner

http://www.renntech.org/forums/index.php?s...le++body++clean

http://www.renntech.org/forums/index.php?s...le++body++clean

[brucem]

clean out the MAF, and run some good gas if not 101 octane if you can. and get on the car more often. I see you said you don't drive it hard, I had a good freind that was a service advisor at Porsche. People would come in all the time saying their car is not running good and sputtering, it was due to driving the car like a grandma ;) just flog it more often and drive for what it was built for. Not all the time, just a little bit.

[ianwallwork]

I usually don't push my 996 hard but have opened her up probably 4-5 times. Over the weekend, I banged out 1st and 2nd gear and there was something different this time. From around 6-7K, the acceleration would start to break up a bit. Anyone have an idea what may be causing this? It's an 02 with 30K miles...Thanks!

The Variocam Plus changes the inlet cam timing at around 6000rpm on a 3.6 (The 'Variocam' bit of Variocam Plus). If you are getting problems only above 6000rpm this is the most likely cause. It also switches from the mild to hotter inlet cam profile at about 3400rpm (the 'Plus' part of Variocam Plus) - you can usually feel this at part throttle. If that wasn't working, it would strangle the engine completely from 3500rpm up .

If it was a bad MAF, it would make itself felt any time the engine is not running closed loop which is mainly at or near full throttle at any rpms. Again this doesn't fit the symptoms exactly.

The PST-2 / PIWIS can test the Variocam operation in seconds. Best take the car to your stealer!!

Ian W

Edited November 25, 2006 by ianwallwork