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Was wondering if anyone could explain the general behavior of the wastegate on this engine. Specifically, I'm looking at a 2017 Golf MK7 GTI, but these are just some general questions:

  1. For starters, the wastegate actuator isn't regulated mechanically by the boost pressure, but electronically, correct?
  2. I assume when the car starts, the wategate is closed, and at around a certain PSI, it opens. For a stock ECU, at what PSI does the wastegate tend to actuate?
  3. Is more boost pressure relieved by how open the wategate is, or are there basically just two states for the actuator: open and closed?
  4. There's an adjustment nut on the actuator; what is this for? I've read that the ECU adapts to different positions to regulate boost pressure, so why adjust it at all?
  5. Does the wastegate behave differently *after* full throttle? Or is its behavior just directly correlated with boost pressure? i.e. do different driving scenarios modulate its behavior?

I know some of these questions can't be answered definitively (unless you program the thing for VW?), but even if it's just your best guess or best understanding, it would help. If you can answer to any one of these please chime in as well. Just trying to diagnose some issues here by understanding better how the part works. Thanks.
 

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2007 B6 Passat 2.0T, 1994 E36 M3 3.0L, 2004 Silverado Z71 5.3L
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Was wondering if anyone could explain the general behavior of the wastegate on this engine. Specifically, I'm looking at a 2017 Golf MK7 GTI, but these are just some general questions:

  1. For starters, the wastegate actuator isn't regulated mechanically by the boost pressure, but electronically, correct?
  2. I assume when the car starts, the wategate is closed, and at around a certain PSI, it opens. For a stock ECU, at what PSI does the wastegate tend to actuate?
  3. Is more boost pressure relieved by how open the wategate is, or are there basically just two states for the actuator: open and closed?
  4. There's an adjustment nut on the actuator; what is this for? I've read that the ECU adapts to different positions to regulate boost pressure, so why adjust it at all?
  5. Does the wastegate behave differently *after* full throttle? Or is its behavior just directly correlated with boost pressure? i.e. do different driving scenarios modulate its behavior?

I know some of these questions can't be answered definitively (unless you program the thing for VW?), but even if it's just your best guess or best understanding, it would help. If you can answer to any one of these please chime in as well. Just trying to diagnose some issues here by understanding better how the part works. Thanks.
1) Correct

2) It's a little more nuanced than that but the general rule of thumb is that the wastegate actuates and cracks open when specified boost is exceeded and then held to the extent that the ECU determines it is time to crack the wastegate slightly so that the actual boost will not climb anymore but will also stay above specified. Generally speaking a full throttle pull from lowish RPM (say 2-3K RPMS) to redline should look something like this: WG closed and WG duty cycle (N75 valve) very high, or more likely maxed, so that boost climbs rapidly, actual boost meets specified boost within 800-1000RPMS of going WOT, actual boost then rises somewhat above specified (~50mbar give or take a bit) and stays that way until about 1000RPMS before redline (if stock turbo), meanwhile WGDC drops a bit which means WG is actuating and cracking slightly so you don't overshoot specified boost too much, approx. 1000RPMs prior to redline both specified boost and actual boost taper down but actual boost should remain above specified the whole way down. Again, that is for a WOT pull from ~2K to ~6K RPMs, basically the kind you would do for data-logging an issue; the behaviors and trends differ somewhat during normal, day-to-day driving. This is at least how my generation of VW and pretty much any VW with K03 will behave and the behavior doesn't change much whether stock or tuned, the numbers do of course though. I would assume it's roughly the same trend in behavior for the Mk7 Golf but since it has a different turbo and ECM it may not trend quite the same; The newer models aren't exactly my wheelhouse but I'd be surprised if it's much different.

3) The former. It's not just two states, the degree to which the WG is open has an affect.

4) Interesting, sounds like VW brought back the external adjustment nut on the actuators rod for the newer models/turbos. They had these on the Mk5 (EA1333 and possible Gen 1 EA888) but the Gen 2 EA888 does not have external adjustment not the ones I've been under. Anyway to answer your question, it adjusts the amount of preload on the wastegate which determines how easily or not easily the wastegate will open. With stock car you should never have to touch this. You really shouldn't have to touch it for a tuned car either but I have found personally for the K03 on my B6 Passat (for all intents and purposes same as a Mk5 Golf) that aggressive tunes requesting more than 20PSI of boost can be too much for the wastegate. I have had to adjust the preload on my wastegate by a total of 3 turns to enable it to actually hold shut properly under WOT pulls. I can only attest to this being necessary in those circumstances on the K03 model equipped on my generation of VWs and possibly later revisions of the K03, but I can't attest to whether it would be necessary on newer generation VWs with aggressive tuning... in other words, WG on the newer models' turbos may be more capable/robust and may hold up to higher boost than before. If you want to understand more about this, why certain levels of boost can potentially cause issues with the stock turbo wastegate functionally in the first place, etc. then read post #40 and #47 in my thread (link below). They are long but should be very informative, should also probably overlap enough to show you a thing or two about how to troubleshoot this issue you said you are having.

5) I think you already know the answers to this question based on what I've already explained, and will understand even more after reading the posts in my thread I mentioned

_________________________

So what is the issue you are having anyway?

Here is the link to the thread (read posts #40 and #47 on page 2). Also second link is to a video made by Brett from Go Fast Bits turbo/WG function. It's short, sweet, and well done. He has a number of other similar vids in that series that you may be interested in too. Great company, great guy too.

http://forums.vwvortex.com/showthre...ly-Seemingly-NO-boost-loss-or-vac-leak!/page2
https://www.youtube.com/watch?v=EI7W7AorDww
 
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