PDK Revs Fluctuate Constant Throttle

[Jabbah]

Thought I would try this with the wider audience of Porsche General...

Whilst gently accelerating the revs are surging up and down by about 100rpm. It's most notable between 1.5K-2K rpm and in higher gears. It's like the clutch keeps slipping every second or it's thinking about disengaging to shift gear but then decides not to. I've also noticed the behaviour gently accelerating out of a bend or off a roundabout, feels like the back end is squirming in time with the rev fluctuations. It's a 2010 997TTS and still under warrantee thankfully. Here are a couple of videos showing the behaviour:

https://www.youtube.com/watch?v=nhoXhb1LHNI

https://www.youtube.com/watch?v=qCJMUYApG5c

[Glenncakeman]

I have same car, and actually recall this happening the odd time too, wondering at the time if I was going mad, or was that the revs actually fluctuating on their own.

[Magic919]

Drop it in and see what Porsche can find.

[lowndes]

This may be incorrect but I seem to recall the turbo has "virtual gears" which are achieved by engaging two gears simultaneously and slipping both clutches.

[Jabbah]

lowndes said:

This may be incorrect but I seem to recall the turbo has "virtual gears" which are achieved by engaging two gears simultaneously and slipping both clutches.

This looks like something new on the 991.2 Turbo PDK. Mine has been back in twice though with "Transmission Emergency Run" recently, so I wonder if they tried a software update. Didn't notice this behaviour before it last went in. They've asked me to take one of their service guys out to show them the issue though. Sods law that it won't be repeatable now...

[ScienceTeacher]

lowndes said:

This may be incorrect but I seem to recall the turbo has "virtual gears" which are achieved by engaging two gears simultaneously and slipping both clutches.

I also understood this to be correct. I suspect it is when you are on light throttle, as perhaps you suggest, and the car can't quite make up its mind. What it is offering you could in some ways be better than an individual ratio, perhaps in terms of fuel economy - though this seems hard to believe. Not sure the clutches benefit!

[Magic919]

Does sound like the virtual intermediate gear feature. Would be good if there was an override, like putting it in manual, or sport mode to switch it off (as a test). Hopefully just a controller problem.