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Hi all, I have been lurking here for many years and i am on my 11th 911 at the moment (2017 991.2 Carrera S PDK) which is an awesome machine, however, i have a small issue that is bugging me...
The stock car has a reported 420PS and 500nm's which is an excellent upgrade from my old 997 Carrera S, however, i am greedy and wanted more so fitted a VRTuned box which has given it ~520PS and ~645NM's !!!
I can pull timed 3-second 0-60s now using launch control, and the car acts like a tuned high performance motorbike through the gears (i get wheelspin in 4th with traction control on!) - animal!..... HOWEVER.... - in 6th and 7th from low revs ~2500 the gearbox slips or "rides the clutch" until i let off the accelerator and press it again when it seems to engage/lock clutch and accelerate.....
My question is - is my PDK faulty? (i assume 645NMs is nowhere near the limit of these PDKs?) - my car has just over 10k miles on it.... any advice welcome!
The piggy backs work by intercepting signals from various sensors and report the data incorrectly as to increase power. This is why they are not always a good idea. My guess is that the torque is getting under reported from the ecu and the trans isn't requesting as high of a clutch pressure as it should and that is why it is slipping.
I would remove the piggy back and see if it gets better. This is why an ECU flash is generally better as it is not tricking sensors, it is making changes to table data.
I would also recommend if you do remove it a PDK relearn from your local dealer to make sure the touch points are corrected from the slipping.
The piggy backs work by intercepting signals from various sensors and report the data incorrectly as to increase power. This is why they are not always a good idea. My guess is that the torque is getting under reported from the ecu and the trans isn't requesting as high of a clutch pressure as it should and that is why it is slipping.
I would remove the piggy back and see if it gets better. This is why an ECU flash is generally better as it is not tricking sensors, it is making changes to table data.
I would also recommend if you do remove it a PDK relearn from your local dealer to make sure the touch points are corrected from the slipping.
Good luck!
-Mitch
Good info, thanks.
So my next question would be; if i took the VRTuned box off and fitted an accessport with a COBB Map what gains would i expect to see? (I am used to the power now!) and would that tune work correctly with my PDK as you describe?
On the 991.2 PDK, the transmission can purposely create a virtual gear using controlled slippage. Like Mitch is saying that tuning approach is probably confusing the programming of that.
Here is the brief section on that from Porsche's Techniks manual:
2.9.6 Virtual gears
The virtual transmission ranges already familiar from the 911 Turbo were implemented in conjunction with the PDK to increase efficiency. If the transmission control detects that the vehicle is travelling at a constant speed at low load, it shifts to a higher gear until the engine would in theory turn at approx. 800 rpm. This presents an enormous fuel-saving potential.
To maintain driving comfort, the transmission control increases the engine speed automatically through slight slip, but only within a range that does not increase wear. The driver remains totally unaware of these sophisticated technical processes.
And here's a slightly more understandable version I found in a press release for the earlier implementation in (capital T) Turbos. This almost certainly sounds like what you are experiencing... but I guess you are noticing it more strongly with the tune.
PDK with virtual intermediate gears
Further development of the Porsche Doppelkupplungsgetriebe (PDK) transmission plays a significant part in the 911 Turbo models’ performance and fuel economy improvements. Porsche engineers supplemented the seven primary driving gears with virtual intermediate gears that further improve fuel economy and comfort. The virtual intermediate gears reduce
engine speed during constant speed cruising when the next higher gear would reduce engine too much. This function is achieved by partially engaging two adjacent gears simultaneously while slipping both clutches slightly to achieve an effective gear ratio in-between them. When acceleration is called for, the Doppelkupplung rapidly exits this mode and down shifts. Since the PDK employs dual wet clutches (oil-bathed), the virtual intermediate gear function results in no added wear.
Hi, as an update (and advice for future purchasers) it turned out to be the VRTuned box from Vivid Racing - the torque map in the box confused the pdk and did not work at all - i took the box off and had the car tuned via obd2 professionally and it works perfectly - no issues at all!
Hi, as an update (and advice for future purchasers) it turned out to be the VRTuned box from Vivid Racing - the torque map in the box confused the pdk and did not work at all - i took the box off and had the car tuned via obd2 professionally and it works perfectly - no issues at all!
thanks!
Glad it all worked out.. Stay away from that crap place vivid racing. It's one of many laughing stock shops in the Phoenix area.
My Porsche Dealer Refused Help re PDK Temp Sensor Problem
edit: Sorry, I meant this for the 997 sticky on pdk repairs - Jeff
All -
Just as an FYI, I am providing my Porsche dealer's response to my request for assistance regarding my 2009 C2 going into "limp mode" on track, with the problem persisting even after having a Porsche 3rd radiator installed. Since I bought it from them in 2018 telling them I was going to track it, and this dealership is a sponsor of my local PCA, I had hoped they would offer at least some assistance without having me pay full price. Not a chance apparently.
I did provide them a copy of the official Porsche service bulletin from this sticky (I did not refer to this sticky though just in case Porsche might try to take it down). I will be looking for a shop or other Porsche dealership that is closer to my home for the PDK temp sensor repair, as I do not think they are acting honorably. Was there a recall or a warranty? No, but in this context I'd hope for something more. YMMV.
Dealership Response"Hello Jeff,
Thank you for your patience. As was explained to me by the service manager, Porsche certainly did issue a bulletin regarding the defect before your purchase of the car, but a bulletin is to inform the dealer network as to the issue and how to rectify the problem, and is not a campaign or recall which requires addressing the problem proactively due to safety as required by the government. Thus, the replacement of this part is not considered as warranty, and will not be absorbed by Porsche North America or the dealer. You’re more than welcome to contact Porsche Customer Service should you care to pursue the matter. I’m sorry that I don’t have better news, but again, this was simply a bulletin and not a campaign nor recall."
Last edited by Janton9736; 01-13-2020 at 01:25 PM.
Reason: typos
edit: Sorry, I meant this for the 997 sticky on pdk repairs - Jeff
All -
Just as an FYI, I am providing my Porsche dealer's response to my request for assistance regarding my 2009 C2 going into "limp mode" on track, with the problem persisting even after having a Porsche 3rd radiator installed. Since I bought it from them in 2018 telling them I was going to track it, and this dealership is a sponsor of my local PCA, I had hoped they would offer at least some assistance without having me pay full price. Not a chance apparently.
I did provide them a copy of the official Porsche service bulletin from this sticky (I did not refer to this sticky though just in case Porsche might try to take it down). I will be looking for a shop or other Porsche dealership that is closer to my home for the PDK temp sensor repair, as I do not think they are acting honorably. Was there a recall or a warranty? No, but in this context I'd hope for something more. YMMV.
Dealership Response"Hello Jeff,
Thank you for your patience. As was explained to me by the service manager, Porsche certainly did issue a bulletin regarding the defect before your purchase of the car, but a bulletin is to inform the dealer network as to the issue and how to rectify the problem, and is not a campaign or recall which requires addressing the problem proactively due to safety as required by the government. Thus, the replacement of this part is not considered as warranty, and will not be absorbed by Porsche North America or the dealer. You’re more than welcome to contact Porsche Customer Service should you care to pursue the matter. I’m sorry that I don’t have better news, but again, this was simply a bulletin and not a campaign nor recall."
Ask for the PCA discount?
2009 C2 - old car 997.2- 1st gen PDK
2017 + 991.2 is a 2nd gen PDK
They are not the same gearbox., but share most parts.
I purchased 2013 911 Carerra (that means 991.1) automatic; on 9/11/20; 44,000 miles; PPI completed - no major issues; purchased from dealer; no warranty; first Porsche ever. Drove it from IL to Kansas City. Detailed problems thus far see below. My mechanic is reviewing this week. I suspect a new PDK, approx 17k.
Does anyone know who can re-build my current PDK? - I know parts can be hard to come by... I'm calling out to several people, not getting much headway.
Does anyone know who sales refurbished PDK?
Have not taken to Porsche dealer to beg mercy, thoughts on this or any other recommendations would be appreciated.
08-13-2018, 10:14 AM
991.2 PDK Slipping? any guidance welcome
