First post! I've got a question for you gurus out there...

I own a 2009 997.2 C4S with PDK which I purchased 18 months back just after the warranty expired, taking a very big leap of faith in the process. This is my first experience with PDK, having always had manuals previously. The car and transmission have performed flawlessly with the exception of low speed drivability while in traffic. I find that the PDK will downshift into first gear once the car has come to rest with an annoying audible and palpable thunk. In order to avoid it, I find that putting the car in sport plus mode so that it will hold the gear is the only way to prevent it. After reading what I can find, I keep hearing references to the PDK’s poor low-speed drivability, but never have I seen any detailed description. Should I assume this is normal behavior, and if so, are there any remedies beyond what I mentioned above? Has this been improved in later models? I called a local dealer and he said bring it in but he didn't comment otherwise. It sounds as if I should be prepared for the answer, "They all do that." as this is not exactly an easily serviceable item.

Rusty Chapman
Fairfax, VA

 

I have an '09 C4S as well. My car does not have a "thunk" when downshifting into first. My complain is that the transmission will not downshift into first unless you really come to a full stop. If you keep rolling even a little bit, the car starts off in second when you accelerate again, and it feels like you are lugging the engine. If the downshift is as rough as you say, maybe it is not normal, and a dealer should have a look at it.
My wife has a '12 Boxster with PDK, and it seems to be better in all drivability aspects, so maybe Porsche made improvements over the years.

 

I drove my 09 PDK exclusively in manual. I was in the habit of always clicking to 1st when coming to a complete stop just to avoid the delay of the system engaging 1st. If this is a characteristic of driving in auto mode, I never did so not sure. But I'm thinking my car would not have engaged 1st until the car was completely stopped.

 

Mine does not "thunk." Or at least not enough for me to notice.

 

In Sport mode the downshift to second then first when stopping is more noticeable and audible, resulting in a bit of a thunk and causing an awkward extra-braking effect just before stopping at times. This was present when test driving the car before purchase, so the dealer let their top tech come drive with me. We experienced it two or three time during the test drive and he said it was just a normal oddity in the car and not a problem. As others suggested, I'm in the habit of doing my own downshifts just to get expected downshift behavior anyway... its unconscious now for the most part.

In non-Sport mode everything is smooth, and after the software upgrade a week or so after purchase the non-Sport mode oddity when rolling to a near stop and accelerating again (a sort of bogging down problem) went away. Non-sport is good since the software update... other than the general tendency to keep RPMs really low in normal driving. I only use it about 10% of the time in slow driving in downtown traffic just to get the smoothness.

In sport-plus mode I'm always in manual, so nothing unexpected there.I've gotten so I use manual sport-plus mode a lot now, the shifts are always what I expect and on the rare cases I'm lazy downshifting at stops, the auto downshifting behavior is more aggressive and seem better than that of plain Sport.

I'm thinking that people who listen to music on the radio might not notice the thunk. I drive in silence most of the time listening to the engineering music of the car, so the thunk is fairly obvious to me on the rare times I'm in Sport and letting to car do things automatically.

 

My 2009 C4S have the described issue only in Sport Mode with air condition on. I had the software updated couple years back and the thunk noise became less noticeable after the update. It is also not noticeable when coasting to stop but more thunk during abrupt stop.

John

 

Definitely clunks into 1st gear. But none is an 11 turbo. Went to the dealer and indeed they said it was performing perfectly. And they said there are no software upgrades. Maybe they did an update that only affects 09s and 10s. I got some info to check which version I should have from another member, but this still would rely on a dealer receptive enough to tell me which version I have.

Indeed, the pdk in the 991 is considerably improved.

 

'09 C2S PDK, with 40,000+ miles. When driving in "auto sport" mode the car has always clunked when shifting on its own to first, unless you were slowing down very gingerly. I drive almost exclusively in "manual sport" mode and in this mode there is no clunk at all when allowing the car to shift down to first on its own when you are coming to a complete stop.

 

Basically the same experience I have with mine- 2011 Turbo.

 

exact same issue happened to a close friend of mine with a 2009 C2S pdk. He complained to the dealer several times and had them check to see if his car had the software update. I think they said he did and he has just accepted the "thunk" as something he will live with. But sport plus was something he said cured it too so it seems software related. I will forward this post to him and ask him to chime in as well.

 

Weird. Never heard a thunk to 1st on my 09 c2 pdk in any mode.

 

The situation described in my original post persisted, to the point that I began to rue the day I ever bought this car ('09 C4S) with a PDK. The perfect solution came along in a '13 991 C4S with PDK. I took it out for a 2 hr test drive and bought the car. The difference is like night and day. It is truly smooth as silk. End of story. Lesson: I should have bought the manual.
Rusty

 

I'm glad you found such a nice workaround. However, I just have to say that you have me scratching my head... you say "I should have bought the manual" but you just bought another PDK, although I understand it is smoother. Curious.

 

What I meant to say was that I should have just gotten the manual in the '09 C4S. Nothing against the PDK per se, although I don't think it was quite ready for prime time back then. Five years later however, the PDK is absolutely stunning.

 

Fully concur as was my experience also.