To the Experts:
I've just had my car a little over one month and I'm enjoying it as much as time allows. One question (for now):

When sitting at idle, I can feel the vibration of the engine behind me, almost as if it's shaking to be released! It's actually an exciting feeling, like I'm in a race car, but a know-it-all friend (and not a Porsche guy) says that something must be wrong with my engine mounts. He hasn't yet been in the car. Again, the vibration is apparent though subtle, but doesn't shake me about; it's a noticeable characteristic but cool to me. I've just not had a performance car before.

The car is CPOd and nothing came up regarding this. I think it's normal, but would appreciate your opinions. If it's not right, I'll gladly stop by the local dealer.

thanks again--

 

Never sat in a 997 without or with an X51 power kit installed. But the engine's quite a tuned engine and tuned engines can be a bit lumpy at idle.

You should have sat in my 06 GTO with its 6.0l 400hp V8 when the engine was idling.

Now my 02 Boxster idles like a sewing machine but my 03 Turbo -- 3.6l 420hp -- is kind of lumpy. Especially when cold.

There is no way I can or anyone else can say if the idle behavior your car exhibits is normal. One has to be there.

It doesn't hurt to pay a visit to the dealer and ask the service manager if he can spare a minute and check things out, provided the vibration is present after the engine is warmed up.

Sincerely,

Macster.

 

Thanks Macster. "Lumpy" is a perfect description. I'll have it checked.

 

Mine's like that too...I just figured its part of the design of the car. To be honest I love it!

 

I agree--it's really cool. Thanks for the confirmation.

 

.... and female passingers REALLY love it!

 

I wouldn't call mine lumpy. But I can definitely feel it vibrating back there.

 

Yes mine also vibrates a little at idle. It doesn't bother me but I was a little surprised since the flat-6 is supposed to have perfect balance:

"The movement of the pistons in a horizontal engine is all in the same plane, so it creates less vibration than in a V-configuration engine; particularly one with an odd number of cylinders on each side of the engine, like a V6. Unlike the V6 but like the inline-6, the flat-6 is a fully balanced configuration which is in perfect primary and secondary balance. The three cylinders on each side of the crankcase tend to have an end-to-end rocking motion, like a pair of straight-3 engines, but in the usual boxer engine configuration, the imbalances on each side cancel each other, resulting in a perfectly smooth engine. The flat-6 is also smoother than the flat-4 or inline-4 because the power strokes of the cylinders overlap in a four-stroke cycle engine. In these four-cylinder configurations, pistons are 180 degrees apart in crankshaft rotation and start their power strokes every 180 degrees, so each piston must come to a complete stop before the next one commences its power stroke. In the flat-6, each power stroke begins 120 degrees after the previous one starts, resulting in 60 degrees of overlap between power strokes and a much smoother delivery of power to the flywheel."

 

When they first start up they are a little rough in the way they feel. The ultimate test is when the vehicle is underway. It should smooth out by then. If not, get it in for a check. These things do smooth out.

 

Did some naughty person change the motor mounts before you?

BD

 

I've got an '05 with the plain 3.6L and can hear a rumbling at idle (a lot worse with the windows open, but thankfully they rarely are) but I can't say I can feel any vibration. It surely is not as smooth as my Mercedes where except for the tach needle I wouldn't know if the car was running or not, but still not noticeable vibration.

 

I have a regular C2. My tach wiggles a bit and the engine is a bit rough at idle. I have had the engine mounts replaced but the lumpiness persists. Dealer ran a bunch of tests (fuel pressure, etc.) -- assures me that the engine is functioning normally and the roughness is normal. Now, I don't know if this is true or not, bc these things apparently vary from car to car. The car does drive beautifully and accelerate smoothly & without hesitation. Taking a wait and see approach. It doesn't seem to be getting any worse, at least.