pcarfan944

The last couple times I let my engine wind out I notice around 5500-6000 it loses its pull and gives off a little shaking or vibration. Tonight I was in a spirited driving mood and was going to try and hit redline in 2nd gear but when I hit around 6000-6100 rpms the engine just jolted and bucked, much like the feeling of when you hit the fuel cut off or a rev limiter. The car has never done that before, and the engine runs great normally and runs out strong until the said rpm range. I know the PO did plugs in the summer of 2002, but not spark plug wires. When I had the 30k service done 2 years ago I believe they also put new caps or rotors in, or both...but other than that it's never had a tune-up while i've owned it (3 years). Any ideas what would cause this? Time for a tune up? Like I said, the car runs great otherwise.

Campeck

run some injector cleaner through the system just for kicks.

our euro 944 does the same thing. not so harsh though. but there is definatly a power loss at 6k.

Yabo

Plugs, wires, coil, dist cap, rotor.. whens the last time you've done these things? Also may be fuel filter if you haven't done that in a while, and that's cheap/easy enough.

Campeck

ha. unless the fittings are rusted. i hate fuel filter changes. bah!

StoogeMoe

Yeah, probably the fuel filter. Can't supply enough fuel for the demands of high revs. If that's true, it should also do it under heavy load like going up a strong hill.
____________________________________
1986 944 NA - Guards Red - 90k miles
1983 944 NA - Platinum metallic - beginning a new life
1985.1 944 NA - Guards Red - donor car
1984 911 Carrera Coupe - Guards Red (gone, but not forgotten)
"If you're not living on the edge, you're not living"

Campeck

this is somethign ive always wondered and i geuss it depends for different cars.

on the 944na is the injector open time longer at high revs and light throttle or low revs and heavy throttle?

oh..wait nvm. the most fuel is injected at peak TQ. which would be around 3.5-4k so flooring it all the way up the rev range would be ..little open time..higher higher higher. and shortening as the revs climb past peak tq. but then their rest time is less...what the hell am i going off on?....

sorry.

Makis

I would also try to change the air filter. Also a blocked CAT will also affect high rpm performance. A air flow restriction has the same effect as fuel flow restriction.

The DareDevil

A few people on rennlist have suggested that tachometer can be off by a couple hundred RPMs. It's possible you were actually hitting the rev-limiter.