I had Sport Mode added to my 2009 CS2 Cab a couple months ago. I've noticed that the car seems to stumble when making aggresive starts from a stop. If I try to give the car a moderate amount of gas from a stopped position the car has a very noticible stumble before it engages. Once it engages it takes off but it is really annoying from a start. The car does not stumble when Sport mode is disengaged.

 

Might consider replacing the throttle body. I replaced mine due to the idle being unsteady and found that overall pedal response and drivability got a heck of a lot better.

It's an easy fix, the throttle body can be had at Roc Auto for under $130 under the Bosch part number. I ordered mine from there and it had the Porsche part number on it too, so it wasn't an aftermarket replacement, it was the real deal that OEM Bosch makes for Porsche.

You should replace the silicone ring gasket too (about $14 from the dealer).

It's actually pretty easy to replace. Less than an hour with ordinary hand tools.

 

Thanks for the input. It's kind of wierd how it only happens when I'm in Sport mode.

 

Yeah, don't know why that might be, other than the programming for the drive-by-wire throttle may be more aggressive.

It's a cheap, easy fix. Worth a shot.

 

I’ve been curious about that momentary lag when flooring the car from a dead stop. My car waits a fraction of a second then launches hard. I thought perhaps the computer was allowing revs to build or measuring traction for the AWD system. But I haven’t googled it yet. Is it normal??

 

Try launch control if you have it. No lag what so ever.

 

Assuming you have PDK? Could it be transmission related? Also, like others have said, it may be the throttle body. Might want to try and clean the throttle body (take off air filter tube and clean the deposits behind the throttle plate) and may want to get some mass air flow sensor cleaner and clean it (follow instructions).

 

If you have a durametric, you could also recalibrate the throttle body.