Replacing KP39 Borg Warner turbo with a Garret VNT17 turbo

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by Tom MacDonald, May 10, 2017.

  1. Tom MacDonald

    Tom MacDonald Member

    Joined:
    Nov 1, 2015
    Messages:
    100
    Car:
    2004 Jetta TDI Station Wagon (North American)
    Location:
    Halifax, Nova Scotia
    So I've been dealing with an issue where my smart actuator on my stock KP39 turbo is no longer "smart".... it still works OK and the ECU seems to be able to apply the correct amount of vacuum to the actuator by using the MAP sensor for feedback but I have a persistent check engine light that is starting to get to me.

    I was considering replacing the actuator with a modified VNT17 actuator as described in How to replace the VNT actuator on a BEW VW TDI engine but I can't quite swallow paying $300 just to replace/modify the actuator when a new turbo is less than $900.

    So, I've been looking for a used smart actuator, but it appears that they are extremely rare and have long been salvaged from all TDIs in the maritimes (I'm guessing the salty local air eats these actuators quite fast).

    So, I've been considering just getting a new turbo. Which brings me to my question as alluded to in the title of this thread:

    Can I use a VNT17 turbo + modified EGR down pipe to replace the KP39 on a plug-and-play basis?

    Do I need to get the ECU tuned as well, or will the VNT17 work with the factory ECU program? If I were to get the ECU tuned as well, what other mods should I get flashed to the ECU at the same time?
     
  2. chittychittybangbang

    chittychittybangbang Administrator

    Joined:
    May 23, 2007
    Messages:
    23,901
    Car:
    2006 Jetta TDI
    Location:
    CT
    The modified turbo will be plug-play as long as the inlets and outlet piping fits, on factory ECU. However, the bigger turbo may spool up slightly slower without a flash. That is a good starting point. The clutch may slip if you dip into the torque too deep during acceleration. If your tuner gives upgrades that's another option. But now you're going into the hole of spending even more money!
     
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  3. Tom MacDonald

    Tom MacDonald Member

    Joined:
    Nov 1, 2015
    Messages:
    100
    Car:
    2004 Jetta TDI Station Wagon (North American)
    Location:
    Halifax, Nova Scotia
    Yea that's kinda what I figured as far as response goes it will be slower and stomping on the gas might make the clutch slip, but sounds like it probably isn't an issue for normal driving.
     

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