John McM

I'm lucky enough to own a Turbo 3.6 and 996TT. The latter is tiptronic and I have to say not as smooth as the Turbo 3.6. I'm talking about vibration at rest, less when in Neutral but still noticeable. Are these cars supposed to be turbine smooth or a bit lumpy? I particulary find it harsh in the 1,000 to 2,000 rpm range, which is where I do most of my driving.

halik

I've got the same thing in idle on my tip 996 4s. One of these days I'll check the trans mount.

Macster

How many miles on the plugs?

Have to say too that driving around between 1K and 2K is imho not a good idea.

These are high performance sports car engines and while they are somewhat tractable at low rpms they do not have the high compression ratio the NA engines have, thus they do not have that low down grunt.

What is partially to blame for the vibration is the VarioCam Plus system which switches to a low lift setting at low rpms.

I adjust my driving to avoid operating the engine at low rpms except in 1st gear and when low speeds are required. 'course my task is possibly easier because I have a manual.

Wouldn't surprise me too that the engine is loaded up with deposits arising from the low rpm operation.

John McM

I have about 5,000 miles on the plugs and have just done a track day so there shouldn't be fouled plugs or deposits. I think I'll run it more in 2nd anyway. I'm also going to get my mechanic to put it up on the hoist and check the mounts. He's already said mounts are not an issue with the cars he sees. Maybe this is normal....just not as smooth as my Turbo 3.6.

Macster

Since I can't experience the vibration it may be more than can be explained by the engine's bit of rawness.

Get the mounts checked. That's a pretty big engine and hung out like it is it can only beat those mounts up some.

Don't know about the fuel situation down your way but have you tried another brand of gasoline?

Also, even though you track the car a Tip equipped car will work to keep the rpms down and this can lead to deposits. So it might be worth running a bottle or two of Techron through the gas tank. Use it according to directions. Best to change the oil/filter after the last tank with Techron gets down to say 1/4 or so.

996turbo4365

have a 2002 996tt tip...smooth at idle...looking to do a paddle shift so I can take it out of auto as I can't get use to doing the button thing.

good luck!

Dans996tt

Mine is smooth. As far as not running at low rpms, not possible with the tip, if you leave it in auto and driving in normal traffic it runs 1500-2500 rpm. If Porsche didn't want it in that rpm range it would shift higher. I run mine in manual a lot but 35 mph is still only 3000 rpm in 2nd gear.

Dan

John McM

As luck would have it today I sat in an idling 996 Turbo with a tiptronic gearbox. It felt very similar to my car. Maybe I'm just too sensitive to vibration. Still at 100,000 miles on the odometer I will get the mount checked, just to be sure. Apparently that's very easy when up on the hoist.

Macster

That could be it. I thought some more about this and I find it hard to believe the engine could be running that rough and not generating CEL and fault codes to go with it.

And in traffic yesterday in a rental Dodge Challenger with automatic (not a bad car...) I got a chance to re-familiarize myself with an auto. An engine would have to be pretty sick to run rough in an auto.

About the only explanation that could make sense in your car's case is the engine or possibly transmission mounts. And even these may prove to be ok.

John McM

Finally got the transmission mount checked. It needs replacing

Carlo_Carrera

Yes, that mount has had it's day.

John McM

Part # 997-375-033-03-M100 = USD 251.50. I'm hoping for an appreciable reduction in vibration when this is fitted.


I see some people try to resurrect the old one with rubber sealant. It would stop the metal on metal harshness, but it wouldn't have the gaps that further reduce the vibration.

John McM

The new mount has been fitted. Vibration at idle up to 2,000 rpm is greatly reduced. The power train also feels a lot more united/taut. Gear shifts are no longer accompanied by a shunt. All good.

I've kept the old one. The rubber hasn't perished it has sheared. This is worse than perishing as the mount loses its integrity in total.