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Help with revs fluctuating

Villa 76

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Joined
9 Sep 2020
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11
Hi,

I'd really appreciate any ideas on a problem with my 997.2 3.6 PDK.

When the revs are sitting around 2000 rpm, without any change of pressure on the accelerator, the revs fluctuate (+/- 2/300 rpm). This doesn't happen at idle and only occurs when I'm cruising, it doesn't seem to be affecting the performance either

I have owned the car for just over 12 months and this problem has been getting progressively worse, though it isn't actually causing a problem so far. I'm concerned though that it could cause other damage, or become a bigger issue.

I wondered if it could be related to 1 or more coil packs? That was the best guess I could come up with.

Any thoughts would be welcome.

Many thanks for any input,
Kevin
 
When this happens can you watch the gear indicator and confirm its not switching between 2 gears .. that will give a rev fluctuation but no perceptible acceleration .

Speaking of which .. do you notice it going faster or the car jerking or is this just you see the rev counter move ?

Things like running faults .. misfires etc and you will feel the car is jerking , not running smooth etc ..

Things like PDK gear change and you will feel nothing .

This does atm strike me as something i would prefer a Porsche mechanic to drive and see what it feels like to him ..

You have said though that it seems to be getting worse ..

depending on the answers above is where i would go with anything from a running engine issue to a software update of the PDK even to its normal .


So .. as always .. a fault code readout of every control unit is needed and a test drive by a mechanic to see what it feels like to him ..

Trust me when i say .. a test drive by us is about the best you can get .. i diagnose or confirm many faults just by doing this .. many of which the customer is unaware of !!
 
Thanks for the response, much appreciated.

I'll get it booked in and have it checked. In response to your questions, there is no change to the gear or jerkiness as such, though you can feel it as well as hear it, but it isn't pronounced.

Like you say probably one for my Porsche specialist to have a look at, just wondered if anyone had come across similar.
 
The Pdk box adapts to your driving style .. it will also have adapted to the previous owners style , there could now be a conflict .. it's possible part of this needs " resetting " .. this is basically setting the values back to standard then reteaching them .

Short term .. drive the car but give it some quick throttle inputs then brake .. do this several times then cruise the car and see if it still surges ...

That would kinda rule out the software for the PDK being the issue .

Getting it checked is best .. a fault code scan will soon say what the issue is and a lack of codes also gives us something to work with .

yes i've had similar on Tiptronics were its the torque convertor clutch lockup and i've seen many software issues with the PDK over the years .
 

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