Help please !

It's not a secret I've been an advocate of PDK all the way.

BUT ... (and please don't turn this into a PDK vs MT war, or an I told you so thread)

... After 4000km I'm allowing myself to go to redline for the first time, still at part throttle. So I thought to myself, lets put the PDK in Auto for a minute and see what everyone is raving about. Holy cow, was I in for a surprise. Unfortunately an awful one. It shifts like crap, so bad I wonder if it is not operating like it should.

Allow me to clarify:
Shifting at redline PDK in Auto Mode, it feels like a novice doing a manual shift too quickly. When declutching, it seems off in throttle control, like it trails the throttle and the throttle rises somewhat. When next gear is selected and clutch is engaged again you get this lurching forward sensation because revs are too high or it rides the clutch, hard to really say. Anyhow, clutch throttle timing seems off !
This lurching is soo apparent it even unsettles the chassis, very much unlike the seamless shifts I am used to in Sport Mode. I wonder if it were to happen at speed in a turn if I'd loose control because of it (something that would not happen in Sport). The car got very unstable on less than perfect roads because of it, even going straight !
Same **** when I put PDK in Manual Mode and went for redline. Same **** when I shifted upwards of 6000-6500 rpm. Below 6000 rpm the problem doesn't seem that apparent.

I mentioned before I never saw the added value of the SC. Well as it stands now, I'll go even farther and state that I hate it ! Sport Plus Shifts are actually much much worse than Sport Mode in my car.

-Anyone experiencing the same, or not ?
-Or am I just being overly sensitive ?
-Or does this go away after a while ?

 

It is "normal", you are not over sensitive, and it will not go away. I also don't like the abrupt nature of the shifts in Sport Plus. I believe Porsche programmed it that way to feel "even more sporty." It's one reason why I never use Sport Plus outside the track (where all the good features of Sport Plus shine through).

 

Maybe I'm wrong but it seems to me that if you're redlining the engine but not at WOT, you're sending a mixed message to the computer as to what your intentions are. Part throttle might be interpreted as, "I may want to hold this gear because I may need to slow down soon" whereas WOT would be interpreted as, "I'm accelerating as fast as I can". You can obviously test this theory to see if you get a different shifting experience. If you get the same results regardless, then I'd recommend taking the car in to Porsche and get it looked at. Doesn't sound right to me, though I've personally never used Sport+ and redlined the car yet.

 

I didn't respond earlier, because when I've shifted in Sport+, I've always been in manual mode. And I missed the part about "part throttle". Your response makes total sense. Why would someone pushing the car to red line NOT be WOT? The ECU may not be configured for this.

When on track, most of the time, I'm 100% flat out, or 0% (while modulating the brake pedal). A very small portion of the time, I'm on both (regardless of PDK or manual). And I'm usually only part-throttle when STAYING in gear (as was mentioned above), attempting to use the weight shifting to point the nose somewhere else, or keep steady through a particular section.

Basically, I'd suggest that if the shifts seem abrupt, try again at WOT. And then see if it still seems out of place (the shifts may be identical, but appear different because the condition changed - you applying more throttle).

(Note: This experience applies to the 997 C2S & C4S, not the 991; I have not driven a 991 C2 on track, nor in Sport+ mode)

 

Sport+ is really only usable and safe on a track, as you said, partial throttle application in sport+ does unsettle the chassis, which is why I never use it on the streets. As KonaKai said, this is the ONLY way to drive at the track, though, where it is telepathically good.

 

I agree with you and Jasper ! You guys make a fair point. I must check it out at full throttle before I make a final conclusion and/or swing by the dealership !
To be continued...

 

Totally agree.
I have a 2011 4S PDK.
17k miles since purchase Nov 2012.
2 Track Events, NJMP and Watkins Glen.
Yours is working as it should.
I now NEVER (almost never) use Sport Plus on the street.
I told my brother, don't even bother with it on the street.
I said the car keeps telling me go faster, faster, faster!
It's too damn annoying to use around town.
BUT on the track, driving like hell...it is a Sweet Experience to behold!

Stick to Sport!

 

Part throttle is the problem here. Porsche programmed the PDK this way in Sport+ because it assumes you are at WOT. I always drive the car in Sport+ but always in manual mode and to me this is the only way to go. You decide when to shift at whatever RPM you want and it shifts even smoother to me because of the engine mounts engaged. PDK shifts faster, dynamic engine mounts are engaged, and driving experience is much better. Now if one is leaving it in "auto mode" in Sport+ then it is quite annoying unless your on the track because it doesn't want to shift until redlined and your left driving at 30 mph in 1st gear at 7K rpm's lol.

 

Isn't sport+ mapping meant to give that jerky super car full throttle performance sensation? I actually enjoy it a lot...!

 

I agree with Sanibel.

 

The hard shift you are experiencing is normal when you understand how an automatic transmission works. When the car shifts from one gear to the next hydraulic line pressure is involved. The more pressure there is, the harder the shift. To be able to get the PDK to shift as fast as it does Sport mode requires increased line pressure.
You would get the same effect if you had a manual transmission and you were able to both shift gears and engage and release the clutch in a low millisecond time frame or if you dont take your foot off the gas when you shift and change gears...i.e. a power shift (or the money shift for those that dont do it right).

Also consider when the car shifts from say first gear to second, that when the RPMs drop they do not drop back down to zero, they are farther up in the RPM range where the engine is making more power (torque and HP)..toss in the torque multiplication due to the higher gear and you can see how things are working.

The shift is hard because the Sport+ mode tells the computer that controls the transmission to increase line pressure to give you a faster shift and that faster shift is felt when the next gear engages.

If you are worried about breaking something I would say you have nothing to worry about. The drive line for the 911 is pretty stout to be able to handle the hard shifting that takes place when launch control is used and remember the car shifts when its making peak power.

 

The first time I experimented with Sport + in auto mode was on a rental 991 in Stuttgart traffic. Drove me nuts with the instant/abrupt downshifts to 1st. Took me a while in my own 991 to learn that in the city (where I use Sport+ in manual mode 90+% of the time as long as engine warmed up thoroughly) it's pure joy. I agree partial throttle at red line is going to confuse the transmission programming.

 

Disagree completely.

I always do sport let alone sport+ when I get oil temp over 180F AND I do use sport+ quite very often. This is how the PDK is mapped--and oh yeah, I'm not guessing/assuming...checked with very well reputable Bay Area Porsche service manager at the time of the break in..it's absolutely normal, nothing to worry.

 

I used to use sport almost exclusively, then switch to sport plus all the time. Now I use sport plus (once engine is warmed up) and put the transmission in manual. I shift using the paddle shifters. I think this is the most enjoyable way for me to drive the car - no jerky shifts and all the chassis benefits of sport plus.

 

Completely agree with those that use Sport+ in manual mode on the street. To me, the shifts are more crisp. I don't use Sport+ in auto, although I did on the track during the Porsche experience trip.

ChuckJ