Welcome to 911UK
The only place for Porsche, 911uk is the definitive enthusiast and resource site for the Porsche 911.
Registration is fast, simple and absolutely free, so join up today for full access to the site and benefit from latest member offers.

Porsche Classifieds
Porsche Buyers Guides
Sell Your Porsche on 911uk
Create a Free Classified Advert
Search Ads
Classified Adverts FAQ
Trade Classified Information
Buyer & Seller Fraud Protection
Pre Purchase Inspection (PPI)
Porsche Car Sourcing
Porsche Cars Wanted
Model
Stock
Porsche 911
991 : 2011- 7
997 : 2004- 65
996 : 1997-2005 37
993 : 1993-1998 7
964 : 1989-1993 0
Carrera 3.2 : 1983-1989 0
Carrera SC : 1977-1983 0
930 Turbo : 1975-1989 1
Early 911 : 1964-1977 0
Porsche Other Models
Classic : 1950-1965 0
Boxster : 1997- 13
Cayman : 2005- 18
Cayenne : 2003- 9
Macan : 2014- 1
Panamera : 2009- 1
912-914-924-928-944-968 5
959 - CarreraGT - RaceCar 0
Car Parts For Sale & Wanted
Other Items For Sale & Wanted
Wheels Tyres For Sale & Wanted
Number Plates For Sale Wanted

Porsche Services
Porsche Body Shop Repair
Paint Protection & Body Wrapping
Porsche Classic Insurance
Porsche Classic Parts
Porsche Classic Restoration
Porsche Design Collection
Porsche Engine Gearbox Rebuild
Porsche Heritage & History
Porsche News
Porsche Picture Gallery
Win a New Porsche 911

Porsche Parts
Body Parts, Body Styling
Brakes, Clearance
Electrical, Exhausts
Engine Cooling, Engine Electrical
Engine Rebuild, Heating Cooling
Interior Incar, Lighting
Rubber Seals, Service Parts
Steering, Suspension
Transmission, Workshop Tools
Early 911, 911 - 930, 928 - 968
964 - 993, 996 - 997, Boxster
Cayman, Cayenne, Panamera

Porsche Model Range
911 [991] 2011-Current
Porsche 911 [991]
911 [997] 2004-Current
Porsche 911 [997]
911 [GT] GT1-GT2-GT3
Porsche 911 [GT]
911 [996] 1997-2005
Porsche 911 [996]
911 [993] 1993-1998
Porsche 911 [993]
911 [RS] RS-RSR
Porsche 911 [RS]
911 [964] 1989-1993
Porsche 911 [964]
911 3.2 1983-1989
Porsche 911 3.2 Carrera
911 SC 1977-1983
Porsche 911 SC
911 [Early] 1964-1977
Porsche 911 [Early]
Boxster & Cayman
Porsche Boxster & Cayman
Cayenne & Panamera
Porsche Cayenne & Panamera

911uk Site Partners

Post new topic   Reply to topic
Author Message
Jabbah
Newbie


Joined: 17 May 2017
Posts: 4



PostPosted: Wed May 17, 2017 12:09 pm    Post subject: PDK Revs Fluctating Reply with quote

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

Is this just normal behaviour for the PDK or something I should get the dealer to sort out? When I took it in to show them the tech agreed it was odd behaviour, but now I've left it with them they are saying they tried another identical car and it does the same thing so must be normal. (Or that car has the same issue!) I didn't notice the behaviour before it went in to them to have the temp sensor replaced a few weeks ago but hadn't used the car that much at that point so could have missed it.
 
  
View user's profile Send private message
   
Norfolk & Idea
Hockenheim


Joined: 15 Jan 2016
Posts: 722
Location: South Yorkshire


PostPosted: Wed May 17, 2017 1:15 pm    Post subject: Reply with quote

I've never noticed mine doing it, and I'm a bit of a gauge watcher. Is it quite noticeable? I see your lube oil pressure is up and down like a whores draws too which would indicate a genuine rev fluctuation condition.

I'd be thinking along the lines of fueling. Has it had a remap that you're aware of?
_________________
2012 997.2 Turbo Basalt Black
2008 Ducati 1098R (Track)
2016 Macan GTS
2008 Vito Sport- Household Star!
 
  
View user's profile Send private message
   
Huntergatherer
Newbie


Joined: 14 Oct 2016
Posts: 22



PostPosted: Wed May 17, 2017 1:16 pm    Post subject: Reply with quote

Mine is an 09 C2S PDK - never seen this....

...but Im going to check tonight, Im normally not holding steady gong out of bends Question

Certainly doesn't look "normal".
 
  
View user's profile Send private message
   
Jabbah
Newbie


Joined: 17 May 2017
Posts: 4



PostPosted: Wed May 17, 2017 1:54 pm    Post subject: Reply with quote

It's certainly quite noticable when holding a steady speed and going up a steep hill. I first noticed it a trip down to Exmouth after getting it back from the OPC for a PDK temp sensor replacement. You can feel and hear the surging, I noticed it from the engine pitch and seat of the pants first rather than seeing the rev needle fluctuate. As far as I am aware it has not been remapped and is under OPC warranty with the 111 point check done before I bought it. I've checked the firmware version of the PDK and it is on the latest for this model.

You don't seem to get this behaviour when pushing on, so only when cruising. I had wondered if it was something like virtual gearing but that should have only come in with the latest PDK on the 991.2 afaik.
 
  
View user's profile Send private message
   
Norfolk & Idea
Hockenheim


Joined: 15 Jan 2016
Posts: 722
Location: South Yorkshire


PostPosted: Wed May 17, 2017 2:03 pm    Post subject: Reply with quote

It certainly doesn't sound terminal but I'd be pushing your OPC for answers. That would drive me crackers.

Does it 'hiccup' on tick over?
_________________
2012 997.2 Turbo Basalt Black
2008 Ducati 1098R (Track)
2016 Macan GTS
2008 Vito Sport- Household Star!
 
  
View user's profile Send private message
   
davidjf7
Hockenheim


Joined: 21 Oct 2010
Posts: 698
Location: Hertfordshire


PostPosted: Wed May 17, 2017 2:07 pm    Post subject: Reply with quote

I've noticed this with mine in auto mode, especially when it feels like it's pulling too high a gear.

Drive mine all the time in manual now and have never noticed it since Dont know
 
  
View user's profile Send private message
   
Demort
Sepang


Joined: 21 Mar 2015
Posts: 2775
Location: Sussex


PostPosted: Wed May 17, 2017 7:35 pm    Post subject: Reply with quote

There were rather a lot of software updates for various faults with the PDK , i would suggest reporting your symptoms to OPC and then they can put a ticket into Porsche for a possible update solution .

It may also be that when the temp sensor was replaced they didnt do a calibration so the box is still in its old settings that it had with the faulty sensor.

Again different calibration routines for different faults .. Opc is best port of call on this i feel .
_________________
Mechanic

7pm - 9pm
 
  
View user's profile Send private message
   
Huntergatherer
Newbie


Joined: 14 Oct 2016
Posts: 22



PostPosted: Wed May 17, 2017 7:48 pm    Post subject: Reply with quote

Ok, checked on the way home - nothing like this.

Surging in my mind would point to fueling or throttle position sensor...sorry can't help.
 
  
View user's profile Send private message
   
DucatiRob
Suzuka


Joined: 22 Jul 2015
Posts: 1066
Location: Milton Keynes

2006 Porsche 997 Carrera 2S

PostPosted: Wed May 17, 2017 9:48 pm    Post subject: Reply with quote

Sounds like a fuelling issue to me, I had something very similar on my Merc, surging on a constant throttle, almost like it was trying to change gear. I had a split intercooler hose that was causing the problem, easy fix. Maybe something similar Question Although if it was you would probably hear the hissing noise of escaping air!
_________________
Present
Carrera C2S Manual
Mercedes CLK DD
Ducati 996
 
  
View user's profile Send private message
   
Jabbah
Newbie


Joined: 17 May 2017
Posts: 4



PostPosted: Thu May 18, 2017 9:21 am    Post subject: Reply with quote

Interesting point on the Merc. I've only had the car a few weeks and as soon as I drove it out of the OPC I got a Transmission Emergency Run light that turned out to be a broken boost actuator rod. They fixed that and then it was ok for a week until the light came back and it was the PDK Temp Sensor that needed replacing. So cetainly could be something along those lines.

They've checked all the ECU and logs but couldn't find any errors, which doesn't mean a lot really. I wanted them to do a running log of rpm and wheel speed etc to check exactly what is happening but they seem to have to go to through PCGB Technical before they can do anything not on the list.

Anyway, hopefully PCGB tech will come back with a solution and it just requires updates or calibration.
 
  
View user's profile Send private message
   
Les
Hockenheim


Joined: 03 Mar 2014
Posts: 672
Location: Up the creek looking for a paddle.

2008 Porsche 997 Carrera 2

PostPosted: Fri May 19, 2017 8:16 am    Post subject: Reply with quote

Mine is normal as well, so somthing is wrong. Can you feel the surge?
_________________
.
According to Chris Craft, I'm officially the 'Unluckiest 911 owner in the world'.
5 x 911's and 4 catastrophic engine failures. So far so good with Porsche no. 6

 
  
View user's profile Send private message
   
Demort
Sepang


Joined: 21 Mar 2015
Posts: 2775
Location: Sussex


PostPosted: Fri May 19, 2017 7:35 pm    Post subject: Reply with quote

Any warrenty work has to be athorised by Porsche .. a no fault found like they have done will not be a warrenty claim so they have already done that work for free .
_________________
Mechanic

7pm - 9pm
 
  
View user's profile Send private message
   
Jabbah
Newbie


Joined: 17 May 2017
Posts: 4



PostPosted: Fri May 26, 2017 11:31 am    Post subject: Reply with quote

Quick update, the OPC think they have fixed the issue with a PDK readaptation / recalibration. I will see later when I get it back as they didn't seem to be able to reproduce it before so how they know it is fixed I'm not sure. PCGB said the videos showed incorrect behaviour so at least I know it is unusual. They have also given me the next (major) service for free in way of apology for 3 issues in the 8 weeks since I bought it which I'm quite happy with. Hopefully that will be it now.
 
  
View user's profile Send private message
   
Display posts from previous:   
Post new topic   Reply to topic   All times are GMT - 11 Hours
Page 1 of 1

 
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum
You cannot post calendar events in this forum