98 Jetta AHU throttle pedal feels no resistance and eng only idles???

Discussion in 'VW Mk3 Jetta, Passat TDI and other/older diesels' started by SRHeer, Mar 30, 2012.

  1. SRHeer

    SRHeer Member

    Joined:
    Jul 25, 2008
    Messages:
    49
    Car:
    97 Passat TDI, 98 Jetta TDI, 91 Jetta 1.9 AAZ TD, 81 Caddy project
    98 Jetta AHU throttle pedal has no response on eng RPM - it also feels like mush - no resistance or springing back - car just idles does not respond to pedal postitioning? Would this possibly be a fly by wire pedal potentiometer there hooked up to the pedal and if so how can one test to see for sure if it is - or but maybe it is the injection pump - hope not - how can I eliminate one or the other or tell if it is one or the other?
    Thanks for your input and help!
    Stephen
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  2. Seatman

    Seatman Active Member

    Joined:
    Jul 9, 2010
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    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    Yip, it sounds like your cable may have broke or something inside the tps has broke, either way I reckon you need a new one. (tps = throttle positioning sensor) The tps is either part of the pedal itself or some are up above the clutch pedal. I'm not sure on the Mk3 but if you have a look up there it should become obvious.
  3. chittychittybangbang

    chittychittybangbang Administrator

    Joined:
    May 23, 2007
    Messages:
    22,071
    Car:
    2006 Jetta TDI
    Location:
    CT
    If you have VCDS you can definitely see pedal position through the engine measuring blocks. However, I seem to remember seeing that if the pedal fails completely or goes out of bounds, engine rpm is brought to about 1200 rpm or a high idle.
  4. Seatman

    Seatman Active Member

    Joined:
    Jul 9, 2010
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    5,222
    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    It sure is, that's what happened on my last tdi, that's why I think something else has actually broken so the ecu is still getting a signal. Also you get a flashing gp light if the actual sensor itself is bad.
  5. JIMMYJAMES

    JIMMYJAMES New Member

    Joined:
    Jan 11, 2011
    Messages:
    3
    Car:
    Hybrid Caravelle 1.9tdi conversion
    Have you looked at the throttle potentiometer? Its possible that the nut might have worked loose and caused the arm to move around the splines on the pot. Try tightening it up, 2 minute job:)

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