Lightsped

I have a always garaged black 2008 S2k with 12k miles. The car is all stock except for K&N FPIK (or whatever it is called). Anyways, I got the car out not long ago and drove it at a regular pace for 10 or so minutes. Soon I accelerated briskly onto the interstate shifting at 7500 rpm. Everything was good until I hit 4th gear. When I shifted to 4th the car seemed to loose power. It was almost like the car was halfway in neutral (which it wasn't). RPMs went up, car lost a lot of momentum. I shifted to 5th and the same thing.

This has happened occasionally before too. Same deal. Entering a highway onramp. What could be the cause? Again, car is maintained very well and is all original.

B0neSt0ck

Sounds like you are describing a slipping clutch. Weird with only 12k on the clock.

Lightsped

I haven't had any tranny issues with the car. The car has never been "launched" or driven hard. Car is taken care of. Not a ragged out highschool kid's car. Is there anything else to consider?
Thanks

FWLBP

Seems like way too low miles for a clutch to have issues. I wonder if his clutch delay valve is acting up? This could have the same effect as a bad clutch. I wouldn't think a bad clutch would slip in a taller gear like 4th & 5th. I believe the clutch delay valve is hydraulically operated, but am not sure.

Reckon

Is the car fully warmed up after 10 minutes?

Any CEL codes or other intermittent issues

Slowcrash_101

Try this, floor the car at low rpm in 6th gear, if revs climb but speed doesn't it's a slipping clutch. If both rpm and speed go up equally then it's probably a fuel issue, which happens with cars that are driven sporadically. Try running some fuel system cleaner if that's the case. If that doesn't help you'll have to check fuel pressure, and if that checks out you most likely have a clogged injector as the regulator on the car is very well designed. It might be a clogged fuel filter or pump, but I highly doubt it. just an fyi Wadzii on the forums offers a fuel injector service with quick turn around.

Lightsped

No CEL codes at all.... I'll try the 6th gear acceleration idea.... I am assuming the car is warmed up enough after 10 minutes of in-town driving. The car is garaged so it doesn't get as cold as a car that sits outside. The fuel would have been somewhat old (maybe a few weeks old if I had to guess).

Slowcrash_101

You can have clogged injectors without triggering a CEL if you let the car sit a month at a time. If you plan on having the S as a car you drive every couple of weeks it might be a good idea to pour a little sta-bil in the gas tank.

Lightsped

Got the car out tonight. In 6th gear at low rpms the car does accelerate. Next, I got on the highway (regular speed) and once on the highway I dropped from 6th to 4th and didn't experience any weird loss of power like I did before...

windhund116

Does the "slipping" get worse, as the car warms up? You could have wear on the clutch plate that shows itself only when the unit gets hot. With time, the slipping may be a problem at any temperature --- as the plate wears down more & more.

.
.

.