Notices
 
 

  

User Tag List

Thread: VW T5 Vacuum pump readings

Page 1 of 2 12 LastLast
Results 1 to 10 of 12
  1. VW T5 Vacuum pump readings 
    #1
    Join Date
    Jul 2008
    Posts
    13
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)
    Hi there

    I can't see where else to post this so please correct me if it's wrong.

    The tandem vacuum/fuel pump on a 2007 VW T5 2.5TDI. Does anyone know what vacuum readings I should be getting at idle and under load please?

    I get underboost problems (limp mode) for the turbo and also the brake pedal feels a little harder than usual. To me this would imply a lack of vacuum pressure from the pump or a leak in the system.

    The van has a new turbo, new N75, MAP and MAF sensors, intercooler, refurbed injectors.... smoke tested vacuum lines and high pressure pipes.

    If it's not this then I'm still at a complete loss as to what causes the apparent turbo underboost fault code and then limp mode.

    Many thanks if you can help,

    James
     
    0 0 0
     

  2. Re: VW T5 Vacuum pump readings 
    #2
    Join Date
    Oct 2008
    Location
    Pembrokeshire
    Posts
    13,123
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    22 Post(s)
    20 mm hg , same as a petrol car at idle, but inlike a petrol this reading should stay about the same as you rev it.
    Audi 80 tdi avant with 360,000 miles...
     
    1 0 0
     

  3. Re: VW T5 Vacuum pump readings 
    #3
    Join Date
    Jul 2008
    Posts
    13
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)
    Thanks for your post Zollaf.
    I don't suppose you know what the fuel pressure out the same tandem pump should be do you?

    James
     
    0 0 0
     

  4. Re: VW T5 Vacuum pump readings 
    #4
    Join Date
    Oct 2008
    Location
    Pembrokeshire
    Posts
    13,123
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    22 Post(s)
    it was 100 psi iirc on the old 1.9 pd engines, so imagine it would be about the same.
    Audi 80 tdi avant with 360,000 miles...
     
    0 0 0
     

  5. Re: VW T5 Vacuum pump readings 
    #5
    Join Date
    Jul 2008
    Posts
    13
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)
    I've tested the output from the tandem pump and it pulls a good 30inHG. I disconnected every joint and checked that it pulls the same vacuum everywhere with no drop. All is good.
    Across the N75 valve it sucks at about 22inHG to the turbo vanes. I assume this drop is just due to the internals of the N75 valve.
    The valve works as I disconnected it and the turbo was very ineffective and it went into limp mode all the time.

    So now that I've changed the Turbo, MAP, MAF, N75, checked the tandem pump, refurbed the injectors and had a new intercooler, does anybody have any idea what to check next?

    All I can think of is whether it's fuel related.. Is there a way to check the fuel flow to the injectors.
    If the ECU requests fuel but it can't deliver enough how can you check that?

    My understanding of the 2.5 is now limited when it comes to fueling. So when you depress the accelerator, is it the throttle position sensor that then controls the opening of the injectors via the ECU?
    My thinking is that the ECU sees that you want to accelerate, it then expects a certain boost pressure to be reached when more fuel is injected, this isn't reached because the fuel flow is limited for some reason, the MAP(inlet pressure sensor) then never reaches the ECU requested pressure, then it goes into limp mode.
    I've probably got that all wrong...

    Can someone please help?
    I'm at a total loss of why it's so underpowered and goes into limp mode under load!

    Thanks............
     
    0 0 0
     

  6. Re: VW T5 Vacuum pump readings 
    #6
    Join Date
    Jan 2007
    Location
    Nottingham, England
    Posts
    42,107
    Post Thanks / Like
    Blog Entries
    4
    Mentioned
    108 Post(s)
    Tagged
    1 Thread(s)
    Quoted
    1816 Post(s)
    What is the code number it is generating? Have you done a requested/actual boost graph test in Measuring blocks 011 zones 2 and 3?
    Anthropogenic climate change, the biggest con inflicted on mankind since religion...

    Slava Ukraini
    !


     
    0 0 0
     

  7. Re: VW T5 Vacuum pump readings 
    #7
    Join Date
    Jul 2008
    Posts
    13
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)
    I have yes, and the actual boost pressure measured at the MAP is always considerably less than the ECU requested.
     
    0 0 0
     

  8. Re: VW T5 Vacuum pump readings 
    #8
    Join Date
    Jul 2008
    Posts
    13
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)
    PO299 is the code - underboost
     
    0 0 0
     

  9. Re: VW T5 Vacuum pump readings 
    #9
    Join Date
    Jan 2007
    Location
    Nottingham, England
    Posts
    42,107
    Post Thanks / Like
    Blog Entries
    4
    Mentioned
    108 Post(s)
    Tagged
    1 Thread(s)
    Quoted
    1816 Post(s)
    In Basic Settings 011, the revs are lifted and the N75 cycled, does the VNT actuator move up and down fully and smoothly in this mode? The boost display should change from approx 1000mBar to 1250mBar. If these are OK I would be considering a new genuine AMM but first of all I would do a 0.5Bar system pressure test but not many people have the equipment.
    Anthropogenic climate change, the biggest con inflicted on mankind since religion...

    Slava Ukraini
    !


     
    1 0 0
     

  10. Re: VW T5 Vacuum pump readings 
    #10
    Join Date
    Jul 2008
    Posts
    13
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)
    The AMM was also recently replaced for a Bosch which I believe is what VW use and it made no difference unfortunately.
    The high pressure system has also been pressure tested.
    A new turbo was fitted that made no difference, and then some months later another was fitted as it was thought the initial one may have been faulty.
     
    0 0 0
     

Page 1 of 2 12 LastLast

Similar Threads

  1. vacuum pump
    By abby1 in forum Audi A6 - C5 Forum - 1998 - 2004
    Replies: 0
    Last Post: 31-12-2014, 02:29 PM
  2. Question Vacuum Pump?
    By geordiestig in forum Audi A4 - B7 Forum - 2005 - 2008
    Replies: 6
    Last Post: 12-01-2014, 07:21 PM
  3. How To Exhaust vacuum pump
    By Nemo in forum Audi A4 - B7 Forum - 2005 - 2008
    Replies: 0
    Last Post: 10-03-2012, 01:19 PM
  4. Vacuum pump (tandem pump)
    By audi_130bhp in forum Audi A4 - B6 Forum - 2002 - 2005
    Replies: 0
    Last Post: 15-11-2007, 12:44 PM
  5. electric vacuum pump
    By gaz238 in forum A6 - S6 - RS6 - - Archive Topics
    Replies: 0
    Last Post: 30-03-2007, 04:45 PM
Tags for this Thread

View Tag Cloud

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


 



  


Disclaimer: VW Audi Forum is an "independant enthusiast website", administered in line with guidelines supplied by VAG in the UK, and is in no way related to any of the Worldwide Volkswagen,Audi,Seat,Skoda,Bentley,Bugatti,Porsche or Lamborghini group of Companies. For official up to date information on any of there vehicles, please visit the official websites. Any comments made throughout this website, are the views of the respective poster, and in no way represent the views of the VW Audi Forum Administration, or the worldwide Volkswagen & Audi Group of companies.


VW Audi Forum do not vet and are not responsible for any information which is posted in this forum. All content is viewed and used by you at your own risk and we do not warrant the accuracy or reliability of any of the information.


Copyright: Certain "words", "phrases" and "Images" used on this website by the Administration are "Copyright" of Volkswagen GB, Volkswagen AG (Germany), Audi GB, Audi AG (Germany), Volkswagen Motorsport GB, Volkswagen Motorsport AG (Germany), Audi Motorsport AG (Germany), Volkswagen Racing GB, Bentley, Bugatti, Porsche and Lamborghini. No image can be replicated by anyone WITHOUT the relevant Companies written permission.


All trademarks and copyrights remain property of their respective owners.

No part of the VW Audi Forum website or forum may be reproduced without written permission from the site administration


PLEASE NOTE - PERSONAL ABUSE, ABUSE AGAINST THIS OR ANY OTHER WEBSITE OR ANY COMPANY WILL NOT BE TOLERATED. OFFENDERS WILL BE MODERATED OR EVEN BANNED.


This website and forum are best viewed at a minimum resolution of 1024 by 768.



  



- VW AUDI Forum - The #1 Volkswagen (VW) Group Forum - Volkswagen (VW) - Audi - Seat - Skoda - Bentley - Bugatti - Lamborghini - Porsche - Scania - MAN - Ducatti - VW Audi Forum -


- www.vwaudiforum.co.uk - www.vwaudiforum.co.uk -