981 PDK issue?

[fasterthanlight]

You know that feeling you get when you jump in the car and drive it and think, something’s not quite right. Well in the last couple of weeks, I have noticed that the PDK on my 981 Boxster S is getting a little jerky. After three years of trouble-free operation, something seems to have suddenly changed.

Cold start, pulling away from a junction jerkiness has always been a part of the PDK’s character, I understand this having lived with one for the last 6 years (including 3 years of Audi S-Tronic), but this normally disappears very quickly.

Now the jerkiness seems suddenly worse and quite unpleasant. I am now aware of a "thunk” as gears change, although it’s something you feel as a shove in your back, more than a noise. A prolonged warm up run (so the engine oil temp is >70C) certainly improves matters, but the issue is still there to a degree.

Engine braking downshifts can be particularly jerky and the car doesn’t feel composed at all which is a little unsettling if you’re steering into a corner.

Details of the car:
- Owned from new (2014)
- Miles: 13,500
- Serviced by the dealer to schedule, including oil change service this year (owner’s request)
- Recently taken out an extended 4^th and 5^th year of warranty
- No fault messages associated with gear selection problems or the PADM (dynamic transmission mounts)

I guess another visit to the OPC may be in order this year. Wondering if I should have bought a manual after all.

 

[Motorhead]

Paul,

You're a very experienced PDK user, so clearly something's amiss.

I think a trip to your PC is in order for an evaluation. Thankfully you have the extended warranty, so you'll be covered for any diagnostic and possible rectification work.

The PDK transmission is an excellent - but complex - unit but I'm more than happy to stick with manual 'boxes for my fun cars as long as they're available.

Hope you get it sorted.

Jeff

 

[Peter_Bull]

Cold start, pulling away from a junction jerkiness has always been a part of the PDK’s character ............

Not with my car it isn't. Smooth as silk.

Good job you have the extended warranty.[]

 

[BoxsterLL11]

On "older" automatics, this symptom is often an indication that the transmission fluid & filters needs changing but as your 981 is only 3 years old I doubt this could be the problem though still a possibility.
According to my service book, the pdk fluid first change is at 12 years/120,000 miles (and the clutch oil is done at the same time interval).
As Jeff stated, the PDK box, in fact all modern day auto boxes are very complex and I suspect any number of small faults could cause this issue.
If it lessens as the engine & transmission temperature reaches normal then I am inclined to think it points towards a fluid/hydraulic problem.
I would have a word with your OPC service department.

 

[Robin M]

Use your Warranty. That's what you bought it for ??

 

[fasterthanlight]

Not with my car it isn't. Smooth as silk. Good job you have the extended warranty.[]

In its normal operation from a cold start, I suppose jerky might be an exaggeration, but I'm always "aware" of those initial gear changes. However now, even with the lightest of throttle applications from a cold start, I'm getting an uncomfortable shove in the back with each initial change. Less so in the higher gears where it almost seems normal until say, you take your foot of the throttle and it jumps down from 7th to 6th and I become aware that the usual seamless transition between gears is no longer there.

On "older" automatics, this symptom is often an indication that the transmission fluid & filters needs changing but as your 981 is only 3 years old I doubt this could be the problem though still a possibility. According to my service book, the pdk fluid first change is at 12 years/120,000 miles (and the clutch oil is done at the same time interval).

Yes, I initially thought that a change of the gearbox fluid would be necessary (despite my paltry mileage) until I saw that this is not something that needs to be done very often!

If it lessens as the engine & transmission temperature reaches normal then I am inclined to think it points towards a fluid/hydraulic problem. I would have a word with your OPC service department.

It certainly lessens, but kickdowns and engine braking decelerations feel like they are not as smooth as they used to be.

With the OPC being a 30 minute drive from home, I am dropping the car off there this evening, so that they can drive it genuinely cold on Friday morning and hopefully be better able to diagnose a fault.

 

[Motorhead]

That sounds like a good plan Andrew. The technician can hook up the car to the PIWIS kit to see what's happening and take the appropriate course of action.

It does sound as though it's a clutch pack control/actuation issue but, as far as I know, the PCs can do very little other than to reflash the software and if that fails the whole transmission has to be replaced; although I suppose they're allowed to replace electronic modules. Who knows if the replacement transmissions are brand new or refurbished units..?

Keep us posted.

Jeff

 

[legin]

In vw audi world this symptom would be the mechatronics unit so i guess it is likely to be the porsche equivalent. The solenoids and controller in the gearbox.

 

[BoxsterLL11]

Just as an insight to auto boxes, I also have a 22 year old Mitsubishi FTO with a 4-speed auto box, ahead of its time in my opinion back in the mid-90's.
A few years ago I took off the front casing whilst changing the transmission fluid as the casing was becoming corroded and can become porous, so I took it off to de-rust, treat & repaint.
The picture shows what was behind the cover.
Now this is a box that was designed 30 years ago.

 

[fasterthanlight]

Well the OPC had the car in on Friday and reported that their diagnostics equipment could find no faults with the gearbox. When I arrived, the car was out on some kind of calibration test drive with a technician, to "reset the gearbox learning", a procedure that I was told should remove any unnecessary hesitations / jerkiness. I was a little sceptical, because clearly while the PDK gearbox makes short duration adaptions to your driving style as soon as you start being "enthusiastic" with either pedal, I thought the idea of any longer term "learning" of your driving style was a myth. Nevertheless, whatever they have done, it has improved the behaviour of the gearbox. I need to monitor it for a bit longer to be sure, but hopefully I can get back to enjoying the car now.

 

[AndrewCS]

Thank you for the update Paul.

Good to know, being that my recent and first PDK is a similar vintage. My experience of recalibrating other manufacturer systems was to ensure that they were driven hard on a fairly frequent basis. The A45 AMG had a gearbox temperature gauge which highlighted when it was at the optimum level, time to reach this was twice that of reaching the same for the engine oil. This has led me to apply the same consideration for the CS, prior to being enthusiastic ...

 

[BoxsterLL11]

As stated previously, my FTO 4-speed auto INVECS box which us 22 years old has an ECU.
It teaches itself how you drive and adjusts the gear changes accordingly.
If you have a heavy right foot, it holds on to each gear for longer (like the sport button effect).
If you are just a tootler around town, the gear changes very quickly up to 4th.
Years ago I was told the ECU can be re-booted by disconnecting the battery for 30 seconds, connect back-up and the ECU then has to start the "learning" process from scratch.

Sounds like the OPC have done something similar obviously on the much more complex PDK box.