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FWIW my 12 GTS PDK behaves almost identically to my previous 15 M4 DCT when cold and going into reverse or drive. Some slippage, not smooth until warm... I will say that the BMW unit was lightning fast when warm and in S+ mode. Seems a tad better than my 997 but is a different marque and newer box...
I have noticed the shifts from 2nd to 3rd or 3rd to 4th to be somewhat long. As if I shift in manual and delay releasing the clutch. The car does that when cold or warm and frequently. I have to also mention that it also happens when pressing the gas pedal hard for a little fun.
should I be worried.
I have noticed the shifts from 2nd to 3rd or 3rd to 4th to be somewhat long. As if I shift in manual and delay releasing the clutch. The car does that when cold or warm and frequently. I have to also mention that it also happens when pressing the gas pedal hard for a little fun.
should I be worried.
The shift speed (clutch 1 disengagement to clutch 2 engagement or visa versa) changes with the selected mode. Sport and Sport Plus are much faster than normal mode, it's the way the transmission control unit (TCU) is programmed. It should not feel like it's slipping but there will be a longer overlap between the two as seen in the graphic below. Try playing with the different modes and see if you notice a difference.
Also, shifting can be delayed if you do something unanticipated as the PDK will have the wrong gear set up. For example, if you are steadily accelerating then suddenly slow down you'll notice this as the PDK has the next higher gear set up and needs to switch over to a lower one. This takes time. One other thing is that the TCU stores an adaptation that implements shifts in accordance with previous driving patterns. If you recently acquired the car and the previous owner drove like a grandma, then the TCU will be adapted to that style. The TCU adaptation can be cleared or it will gradually readapt over time if driven aggressively.
I wouldn't be worried unless you've noticed a significant change in behavior recently, it feels like it's slipping, or if the things noted above don't explain what you are seeing.
The shift speed (clutch 1 disengagement to clutch 2 engagement or visa versa) changes with the selected mode. Sport and Sport Plus are much faster than normal mode, it's the way the transmission control unit (TCU) is programmed. It should not feel like it's slipping but there will be a longer overlap between the two as seen in the graphic below. Try playing with the different modes and see if you notice a difference.
Also, shifting can be delayed if you do something unanticipated as the PDK will have the wrong gear set up. For example, if you are steadily accelerating then suddenly slow down you'll notice this as the PDK has the next higher gear set up and needs to switch over to a lower one. This takes time. One other thing is that the TCU stores an adaptation that implements shifts in accordance with previous driving patterns. If you recently acquired the car and the previous owner drove like a grandma, then the TCU will be adapted to that style. The TCU adaptation can be cleared or it will gradually readapt over time if driven aggressively.
I wouldn't be worried unless you've noticed a significant change in behavior recently, it feels like it's slipping, or if the things noted above don't explain what you are seeing.
thanks for the explanation. I tried with different modes. For example, today I was in sport plus and pressing hard. The slippage was felt from 2nd to 3rd while pedal was fully pressed. A few moments later, the same shift was nice and quick.
I have had the car for 2 years now. This always happens and just afraid it might be the clutches going bad. I drive the car hard occasionally thinking she should be tough enough to take what is thrown at her. Around 46k km on the odometer.
Realize this is an old thread. As a Porsche noobs everything is on a learning curve that can go from exhilarating to terrifying, sometimes all in the same drive. For the first month I chased this slip around to the point that I was starting to think the car I just bought had a bad tranny. Then found this thread and for the past few weeks have been able to get it under control to where it only happens when I get sloppy with the gas pedal. Always appreciate a post with a chance to learn from experience - TY!
100% agree. Being a new owner of a new to me 2009 997.2 myself, I often find myself asking “is this normal” maybe that’s an idea of a set of topics for us new ppl to see what normal looks / sounds / feels / smells like...
thanks for the explanation. I tried with different modes. For example, today I was in sport plus and pressing hard. The slippage was felt from 2nd to 3rd while pedal was fully pressed. A few moments later, the same shift was nice and quick.
I have had the car for 2 years now. This always happens and just afraid it might be the clutches going bad. I drive the car hard occasionally thinking she should be tough enough to take what is thrown at her. Around 46k km on the odometer.
Supposedly the clutches are rated for 200k miles (unofficial, but from a couple of sources) and failure is pretty rare. It could be the clutch failing but more likely it's a valve body solenoid or the clutch fluid pressure sensor that regulates the clutch application. Is it more pronounced going into odd or even gears? Clutch 1 is for gears 1,3,5,7, and R, clutch 2 is for 2,4, and 6. They are independent circuits so a failure or glitch in one should have an odd/even pattern in the symptoms. The cooling circuit and overall PDK pressure control are common to both if there is no pattern. Check out the PDK repair sticky here in the 997 forum as this info is documented there.
Edit: Forgot to mention the clutches can be recalibrated by the dealer or someone with a PIWIS clone. This isn't normally required in everyday use but is the first thing a dealer will try if there are engagement complaints. This readapts the clutch engagement/disengagement by putting the PDK in a special mode, performing at least 30 shifts, and measuring data from various sensors in the PDK during this process. From this it generates new adaptation tables for the PDK to use going forward.
30 years ago mechanical evaluation was fairly straight forward.
With all of the adaptive computer over rides today it can be much more difficult.
Drive gently in Sport Mode and before you know it that mode is acting like Comfort mode. And vice versa. In other words ... Don't select Sport unless you're driving like Sport.
If in doubt, reset the system. Or as mentioned above ... Have the dealer reset the parameters.
thanks for the explanation. I tried with different modes. For example, today I was in sport plus and pressing hard. The slippage was felt from 2nd to 3rd while pedal was fully pressed. A few moments later, the same shift was nice and quick.
I have had the car for 2 years now. This always happens and just afraid it might be the clutches going bad. I drive the car hard occasionally thinking she should be tough enough to take what is thrown at her. Around 46k km on the odometer.
For what it's worth, mechanical failures of the PDK seem very rare. I've yet to read or hear about one which obviously doesn't mean one never happened. The more common failures discussed around here and elsewhere seem to be electronics related.
Supposedly the clutches are rated for 200k miles (unofficial, but from a couple of sources) and failure is pretty rare. It could be the clutch failing but more likely it's a valve body solenoid or the clutch fluid pressure sensor that regulates the clutch application. Is it more pronounced going into odd or even gears? Clutch 1 is for gears 1,3,5,7, and R, clutch 2 is for 2,4, and 6. They are independent circuits so a failure or glitch in one should have an odd/even pattern in the symptoms. The cooling circuit and overall PDK pressure control are common to both if there is no pattern. Check out the PDK repair sticky here in the 997 forum as this info is documented there.
Edit: Forgot to mention the clutches can be recalibrated by the dealer or someone with a PIWIS clone. This isn't normally required in everyday use but is the first thing a dealer will try if there are engagement complaints. This readapts the clutch engagement/disengagement by putting the PDK in a special mode, performing at least 30 shifts, and measuring data from various sensors in the PDK during this process. From this it generates new adaptation tables for the PDK to use going forward.
@PV997 I wonder if you have insight about PDK engagement behavior regarding how it behaves under the different brake/gas pedal scenarios?
I have made several posts under your PDK repair thread, long story short - 2 months ago car showed a "transmission emergency run", CEL, threw p0700 p1734, and couldn't reverse (it would rev but feels like the clutch/gear wouldn't engage), I tried to clear the code but whenever I try to reverse errors and codes would come back again. I thought I needed a new distance sensor, and brought the car to a shop that can do it, but they cleared the error, did a full service and PDK recalibration and it went back to working order.
A month later same problem came back, only this time after I cleared the code, the code didn't come back when I try to reverse, although I still can't reverse consistently - if I move the shifter between P and R for around 7-8 times it would eventually reverse.
I was playing around in my garage to see if there is a pattern of when I can get it into reverse, then I noticed something - I usually drive with both feet and when I reverse the car, my habit is to start with the brake pedal depressed, shift into R, and both feet work together at the same time (gradually give gas and release brake at the same time). If I reverse like this it would get roughly 1 successful reverse out of 8. BUT if I just release the brake (not giving gas at all) and wait for the car to creep backward by itself before I give gas, looks like I can reverse almost 100% of the time (although sometimes there is a 1-2s lag for it to start creeping, sometimes longer sometimes shorter)! So it almost feels like part of PDK program says, if engine rev is higher than X while the brake pedal is released past a threshold, don't engage the transmission (to avoid the car shooting backward maybe?)
I have always driven like this since I own the car (for about 3 years) and these "transmission emergency run"/p0700/p1734 recently (very very occasionally I'd see R doesn't engage but I'd just need to put it back into P and R again it would then move along). My hypothesis is my distance sensor 4 is on its way out and acts up intermittently (I have read a few other cases of distance sensor problems initially it errors intermittently before eventually going completely dead), and whenever it acts up and gives a bad reading, it messed up PDK calibration, or just reset the calibration to factory setting? If the clutch is slightly worn, it would have to engage more aggressively to compensate for the worn clutch, if a sensor error reset the calibration, maybe it would explain why my two feet reverse wouldn't work because it wasn't engaging the clutch aggressively enough before engine rev pass a safety threshold?
If my speculation is correct, bad news is I'd need a distance sensor at some point, but I found it interesting that it seems to interact with the footwork of the brake/gas pedals. It's all just my speculation though I don't know how valid is it, just want to see what would be your read of my situation... thanks!
This brings back a memory of a poster who figured that most PDK failures occurred on cars that were driven with both feet. I won't say this is accurate or not. Just a memory without data to open up a possible discussion.
This brings back a memory of a poster who figured that most PDK failures occurred on cars that were driven with both feet. I won't say this is accurate or not. Just a memory without data to open up a possible discussion.
interesting @Wayne Smith , can you point me to that post if possible I don’t think I have came across with it.
interesting @Wayne Smith , can you point me to that post if possible I don’t think I have came across with it.
It was a few years ago and the search function doesn't work on my phone interface. Additionally, using Google, there is a lot to look through to find anything specific.
As I recall the concern was possible heat buildup. Heat and thermal cycles are the nemesis of electronic parts.
Personally I don't see a problem with two foot operation. But someone back a few years ago raised the issue.
It was a few years ago and the search function doesn't work on my phone interface. Additionally, using Google, there is a lot to look through to find anything specific.
As I recall the concern was possible heat buildup. Heat and thermal cycles are the nemesis of electronic parts.
Personally I don't see a problem with two foot operation. But someone back a few years ago raised the issue.
That's ok I will see if I can find it, sounds interesting, although I'm skeptical about it, in my case even if I drive with two feet it isn't like I spend a lot of time with two pedals active at the same time so I'm doubtful on it would create enough temperature increase to cause sensors failure.
04-27-2019, 01:26 AM
