strange thumping sound

[tom__w]

I just recently got back my 06 CS from a Porsche specialist. 40K service with serpentine belt, oil, air filter, etc. $640. Not a bad deal.

Perhaps I have been deaf all this time but when in park or otherwise and I press the accelerator hard, I hear a quick sucking sound and then a thump. It doesn't do it if I press the accelerator gradually.

I don't think it was there before ... or maybe I am just being paranoid. The car seems to run fine.

Is this normal? :(

Thanks

[wvicary]

Doesn't sound normal. Inspect the air filter housings - there are two of them - and be sure they are correctly installed and all connecting air pipes.

[tom__w]

Brought it back to my guy and he looked the the left side air filter assembly. Also took off the center air intake tube to look at the throttle body. He did not look at the right side. All looked fine.

The sound seems to be coming from the middle section (throttle body). Sounds like the throttle body valve slamming (hence the suck / thump). Unfortunately there is no way to run the car and inspect the throttle body with the center air intake tube off.

Performance seems normal .. normal with a slight lag in response, which is normal to me.

Any other suggestions?

Thanks!

[wvicary]

Is the throttle body clean?

[tom__w]

it looked clean to me. are you thinking that the valve may be sticking?

[wvicary]

I have seen the electronic throttle valves stick to such a degree that they have remained closed and cause the engine to flood because it could no longer draw in air. Be sure not only the throttle plate looks clean but also the bore.

[roach2012]

i have noticed the came thing, did you find the cause ?

[RFM]

This is normal behavior on Cayenne V8, when you floor the accelerator pedal hard and in one movement, nothing to worry about.