Jabbah

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:



Has anyone else noticed similar behaviour with the PDK? Just wondering if it is normal or if I should be firm with the dealer that there is something wrong.

voiceprint1

car speeds seems pretty even, never seen behavior like that from the RPM's, is it also happening at idle? unless your really on/off throttle I don't this is typical

I vote not normal

SoCal C2S

Dual clutch slippage?

Never seen this before in any of my friends PDKs.

docdrs

How long have you had the car? Did it just start. Does it happen in all gears, the odd gears ,or just the evens. One clutch operates the evens and one the odd gears. Run the car in manual mode which eliminates the transmission wanting to change gears.

phaphaphooey

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Jabbah

Certainly seems like clutch slippage. Hopefully just some calibration issue, it did have the PDK temp sensor replaced just before I noticed it. Only had the car 3 weeks before this though so I might just not have noticed before.

Seems to happen in most gears, but more obvious in higher ones (4, 5, 6 & 7), certainly both sides of the box are affected.

I've also tried running in manual, sport, sport plus and still get the behaviour. Haven't seen it in cruise control, but that should be trying to keep the revs constant anyway. In cruise control I did notice a rev flick going down hill when it was using engine braking.

It's with the OPC now and they've sent a tech note to the Porsche tech experts so will hopefully get at least an explanation of what's happening.

docdrs

The temp sensor is a known issue, too bad they have to drop the pan and the whole valve body to get to it. Were you getting an over temperature code? Do you regularly drive in sport mode with pasmon regular?

ADias

What is the reason for the question? What does PASM Normal with SC Sport have to do with PDK behavior?

stronbl

I would hope it is not a PDK clutch issue. Not too sure there is a lot of fixes for the unit other than a software recalibration. Your video only showed a small range of rpms and gears - what happens at higher rpms and in other gears? Can you "feel" anything that would suggest a clutch problem? I'm very interested to learn more about this issue you raised.

When I saw your video my initial reaction was a tach / sender unit issue with you gauge, e.g. voltage fluctuation.

phaphaphooey

My curiosity is officially piqued now. Please follow up and let us know what your dealer says.

Jabbah

Not sure of the code, just got an Transmission Emergency Run light. I do fairly often use sport mode with PASM normal. Why would that cause anything?

Jabbah

It is more obvious in higher gears as it occurs more with at low revs with a bit of gas, but I've seen it in every gear from 4th to 7th. You can feel it too which is how I first noticed it. There is a slight but definite surge of acceleration when the revs increase. The engine pitch changes at the same time too. I've noticed it accelerating off a roundabout / bend too where it feels like the back end wobbles a bit with the surging.

Jabbah

Will do.

johnireland

When it comes to PDK, if it isn't working perfectly, it isn't working. Don't waste time asking questions here, get it to a dealer ASAP. Complex technology means fragility in the system. Simple voltage problems can send a PDK into a tail spin. If you notice, more and more car makers are turning away from dual clutch and putting their money into maximizing the old torque converter systems. Rev matching, super fast ****s, etc., etc. PDK is just an electronically controlled sequential gearbox with the dual clutch to give better street drivability. For real racing, look at the WRC...no paddles...and single clutch technology.

golfnutintib

dealer calibration and fluid service called for i believe