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Hello can’t even merge onto the highway without going into limp mode

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by Gonzo_TDI, May 24, 2012.

  1. Gonzo_TDI

    Gonzo_TDI New Member

    Joined:
    May 24, 2012
    Messages:
    2
    Car:
    2000 Jetta TDI
    Hello everyone,

    I have a 2000 jetta w/ 280K miles on it. So I've been dealing with limp mode for a while. About 100K miles ago I replaced all vacuum lines (they were pretty beat), N75, MAF, cleaned out the air canister and snow screen, and conditions improved but didn't go away. I was going into limp mode only once a month vs every other day, so I just kinda lived with it. But things started getting bad again (back to experiencing limp mode every other day or so). So I did a boost leak test and found air gushing through the VNT actuator at 5 psi so I replaced it. But now I can’t even merge onto the highway without going into limp mode. I adjusted the new actuator by counting the threads on the rod and matching it up to the old one. I’m thinking maybe I got the adjustment wrong?
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  2. chittychittybangbang

    chittychittybangbang Administrator

    Joined:
    May 23, 2007
    Messages:
    20,904
    Car:
    2006 Jetta TDI
    Location:
    CT
    The spring pressure could be a little different. Check out the VNT adjustment article in FAQ, you have to use a vac pump to set base and full travel on rod. But it should be close. When the rod was off, you should also move the VNT lever by hand and check if it's free, more inst. in the article.
  3. Gonzo_TDI

    Gonzo_TDI New Member

    Joined:
    May 24, 2012
    Messages:
    2
    Car:
    2000 Jetta TDI
    Thanks chittychitty, the TSB in that FAQ article was key. Took the car for a test drive and so far so good – I guess the actuator just needed to be adjusted. I haven't been able to accelerate like that in years.

    One thing that was surprising was that I really couldn’t get any movement on the old rod using a vacuum pump - I'm surprised the turbo even worked at all with the old actuator. Anyway, Thanks!
  4. crsmp5

    crsmp5 Member

    Joined:
    Feb 14, 2012
    Messages:
    437
    Car:
    85 kubvan
    i had a same issue on a 02... got worse with new actuater even adjusted properly..

    so i finally rigged up a boost gauge and a vacume gauge to watch the vnt actuator vs boost spikes...

    via all that info i deemed the turbo had a issue...

    well finally found a rebuild place, 75miles from home... good people.. the vnt lever inside was worn, vains stuck... total cost 350... that included rebuilt vnt section.. no more limp issues..

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