Overboost troubles

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by xcr600man, Dec 27, 2016.

  1. xcr600man

    xcr600man New Member

    Joined:
    Mar 14, 2011
    Messages:
    4
    Car:
    2003 Jetta TDI
    My 03 Jetta TDI has been going into limp mode constantly. Only way it doesn't is if I watch my boost gauge and not let it stay over 10 psi very long. Has a new actuator, all new vacuum lines, new N75valve. It's making plenty of boost. At wide open it will make 22 psi. Seems like it should have more power than it does. It just won't bleed off. I use to hear it bleed off thru my boost gauge so I know it's definitely not bleeding off now. Any ideas???
    Oh and it's all stock
     
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  2. Erich

    Erich New Member

    Joined:
    Jun 28, 2015
    Messages:
    18
    Car:
    Vw Jetta tdi 2000
    Location:
    burlington
    Sounds like the vanes are not freely opening and closing. Might want to Check adjustment of the actuator arm and or whether the vanes are carboned up preventing the actuator to fully move back and forth freely.


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  3. xcr600man

    xcr600man New Member

    Joined:
    Mar 14, 2011
    Messages:
    4
    Car:
    2003 Jetta TDI
    Would I get 22 psi if they were?
     
  4. Erich

    Erich New Member

    Joined:
    Jun 28, 2015
    Messages:
    18
    Car:
    Vw Jetta tdi 2000
    Location:
    burlington
    If the actuator is unable to move the vanes to relieve some pressure I guess it would over boost yes


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  5. crsmp5

    crsmp5 Well-Known Member

    Joined:
    Feb 14, 2012
    Messages:
    1,254
    Car:
    85 kubvan
    22psi is overboost... so.. what do you not understand?
     
  6. xcr600man

    xcr600man New Member

    Joined:
    Mar 14, 2011
    Messages:
    4
    Car:
    2003 Jetta TDI
    I thought it wouldn't have boost at all. Sorry
     
  7. xcr600man

    xcr600man New Member

    Joined:
    Mar 14, 2011
    Messages:
    4
    Car:
    2003 Jetta TDI
    Where is the best place to send them out for rebuild?
     
  8. koabi

    koabi Member

    Joined:
    May 12, 2012
    Messages:
    69
    Car:
    1998 Jetta TDI, 2003 Jetta Wagon TDI
    Location:
    Tucson, AZ
    you probably don't need a rebuild.

    Your new N75 valve certainly helps, but if the vacuum line from N75 to the actuator isn't good then it doesn't matter. (Does no vacuum mean fail with vanes open or closed guys?)
    If you can, disconnect the actuator from the lever and see if the lever moves freely. Should have about 1/2" of travel. If it doesn't your vanes might look like mine did:
    IMG_20150821_193013738.jpg

    chitty made a good diagnostic video too if you haven't seen it yet:
     
  9. crsmp5

    crsmp5 Well-Known Member

    Joined:
    Feb 14, 2012
    Messages:
    1,254
    Car:
    85 kubvan
    had someone pay me to do ez off method once... id never do it to my own car.. but can try it...

    http://www.xsboostturbochargers.com/
    is a guy who ive had rebuild quite a few turbos... i went to his shop 1st time to check him out and his equipment.. not a half ass shop in any way.. they hand file to fit the oil seals and balance every turbo.. and sandblast/make it look new too...
     
  10. VW_TDi

    VW_TDi Member

    Joined:
    Jun 17, 2014
    Messages:
    30
    Car:
    2005 Passat TDI, 2001 Jetta TDI
    Location:
    California
    This is what I did to my own car about 2 years ago and it helped after swapping all vacuum lines & the N75 valve. I wasn't a big fan of it, but I needed a quick temp fix that would get me to work and back.
     

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