Overboosting Issue

Discussion in 'Modifications And Maintenance' started by Pauline, Aug 6, 2018.

  1. Pauline
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    Pauline New Member

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    This is a bit of a “be careful what you wish for” instance. I drove the car up to BIR this weekend and the car was running great on the way up. I did a few laps on the track, when I realized the car wasn’t hitting full boost anymore. I am tuned to hit around 19-20 peak boost, but the car was only hitting around 17 psi. I pulled off and looked for any leaks, and noticed that the coupler attached to my turbo had come loose. I fixed it and went back out. Except this time.. it was hitting 25 psi and holding around 22-23 psi! The car was boosting so much that it threw itself into limp mode. I limped it off track, noticed that maybe a vacuum line from the boost controller to the EWG was possibly pushing itself off of the T fitting, pushed it back on, and called it a day.

    The car is now boosting to 23 psi with only maybe 1/3 of the throttle being pushed in in 3rd gear.

    We rerouted the vacuum line directly to the EWG to bypass the EBCS, and now the EWG does not open up at all and the car is still hitting 25 psi.

    Next step is to open up the EWG to see if it is a wastegate issue, since we’ve ruled out a EBCS issue.

    Any other ideas?

    The car had overboosting issues before, which is why I installed an external wastegate (which helped up until now).
    ..Maybe my car is just trying to tell me she just wants a bigger turbo? :b

    relevant Mods:
    grimmspeed EBCS
    tial 38mm EWG with an 18 psi spring (I know, big spring for a stage 2 car)
    ETS fmic
    stock turbo..

    2006 STi
     
    Last edited: Aug 6, 2018
  2. Leonnosyt
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    Leonnosyt Member

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    Do you still have the restrictor pill in the wg vacuum line? I had a similar issue where the restrictor pill (tiny brass bead with hole through it in the vacuum line) was corroded and plugged up so the waste gate wasn't seeing any boost and wasn't opening.
     
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  3. Pauline
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    Pauline New Member

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    I put in all new vacuum lines when I put in the EWG, so that’s been deleted
     
  4. joebush44
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    joebush44 Well-Known Member

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    There are 3 bottom ports on your tial gate. You are likely only using one of them. The other two should be plugged, but it's not impossible for those little plugs to back themselves out. This would cause the gate to stay shut - over boosting. The coolant ports, if not using them, can just be left wide open. (FYI - there is one top port on the side which can either be plugged or vented and then there is a port directly on top which can either be vented or plumbed back into the EBCS depending how you have it setup.)

    So, if the two bottom plugs are still in the gate and you have a vacuum line routed directly from the gate to the compressor housing of the turbo and are still overboosting - there must be a mechanical issue with the wastegate. Is it a genuine TiAL or a chinesium knockoff?
     
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  5. joebush44
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    joebush44 Well-Known Member

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    With a pic...

    1 of 3 lower air ports you have a vac line on, but the two other lower air ports should be plugged...make sure one of those little plugs didn't back out.

    Another thing to check is to make sure the vac line is all the way onto the compressor housing nipple and no tears in it. If that hose is bleeding air off before reaching the gate, the gate won't open when it should.

    [​IMG]
     
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  6. Pauline
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    Pauline New Member

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    I will look at the plugs tonight. The Tial is a genuine Tial, I hear the fakes are fragile and can have parts bend which is another thing I’m going to look at. Thank you!
     
  7. joebush44
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    joebush44 Well-Known Member

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    When changing springs, the diaphragm can get pinched when bolting the top back onto the gate. Something to look at as well. Good luck! Hopefully something stupid/easy to fix.
     
  8. Pauline
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    Pauline New Member

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    wouldnt a pinched diaphragm be apparent immediately? everything was just fine n dandy with the wastegate and boost up until she saw the track and then boost got crazy. I’m wondering if there’s a tear?
     
    Last edited: Aug 6, 2018
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  9. joebush44
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    joebush44 Well-Known Member

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    It more than likely would have been apparent immediately if it were pinched. It's possible that it was still functioning with it pinched, just not 100%. Then potentially when you were lettin' er rip tater chip and doin' it for Dale on the track, maybe it finally let loose and tore a hole in the diaphragm.
     
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  10. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    Dumb question, since nobody else seems to have asked it...How long since you put in the TiAL and the EBCS? How many miles would you say you've put on it since the install.
     
  11. Pauline
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    Pauline New Member

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    This is what my setup looks like. I attached the vacuum line directly to the top air port, this is the right nipple to attach it to correct? it looks like the other nipple on the right is a water port, so that wouldn’t make sense to attach it there. There are 3 plugs, 2 on the bottom and one of the left side. I just wanted to make sure that I’m not pulling a rookey mistake and simply setting it up incorrectly before I actually take it apart. All of the plugs are there, so it doesn’t seem to be an issue of a missing plug
     

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  12. Pauline
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    Pauline New Member

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    EBCS has less than 8k miles and so does the Tial wastegate
     
  13. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    So, this isn't a recent installation, and I'll assume you've driven it hard in that 8k miles at some point where you would have found this issue if it were persistent since the install.

    One option would be getting a mix of dishsoap and water, enough dishsoap that it is really slick/soapy, put it in a spray bottle with a mist nozzle. Fire up the car with the hood open, and start spraying down your vaccum lines with the soap mixture to see if it blows any bubbles.
    Vaccum lines, especially with regards to wastegates, are extremely sensitive. And even a miniscule pinhole leak can cause things to jump all over the place. I noticed it mentioned earlier about the "boost pill," which it sounds like you replaced when you installed the TiAL. I doubt you have this, because WOT pulls would result in you hitting full boost and rolling back down to whatever the spring pressure on the wastegate is, and back up and back down, over and over while in full throttle. That doesn't sound like your issue.
    Still, it feels like vaccum line foolery. If you aren't too busy/lazy, replacing all the vaccum lines again isn't a terrible option. I hope your vaccum lines are rubber not silicone, those plastic-y silicone lines crack and pin-hole all the time as they are susceptible to dry rot.
     
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  14. Pauline
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    Pauline New Member

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    I’m gonna go pick up some fresh lines now. That would be such an easy fix if it’s just that!
     
  15. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    It's not a terrible place to start. Occam's Razor. The simplest answer is likely the correct answer.

    And it's cheap, and pretty simple to test. Beyond that, the comments about the Tial spring/diaphram binding have happened to me in the past too. Sometimes it is just a matter of removing the lines, opening the wastegate (usually the top just unscrews) resetting the spring in there, and screwing the top back on. You can likely do that while replacing the vaccum lines as well.
     
  16. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    OH! Be careful when removing the top of the wastegate, as that spring is under tension! It WILL go flying, and can sometimes be a real pain the ass to get back in there.
     
  17. Pauline
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    Pauline New Member

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    Yeah, the pressure is very very high in there. I am wondering how I will get it back in there and back together after opening it. Removing it and opening it isn’t my fear, it’s getting it back together with the spring in there haha. know any tricks before I do it? I’m changing the lines and will test her out after doing so, but the lines are all pretty new so I have an unfortunate hunch that it may not be that
     
  18. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    Brute Force and ignorance. Not going to ask your weight, but whatever it is, you'll want to put all of it into pressing that lid back on that spring. It isn't too much, but you will probably spend a few frustrating minutes before you get it. But you'll get it.

    20lbs of pressure isn't terribly much, and if you can't manage it, you might want to look at your life and make some changes. But it can be a frustrating amount of pressure to apply why trying to line up threads.
     
  19. Pauline
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    Pauline New Member

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    I think I found it! Will not be putting the t fitting so close to my turbo this time around. thank you all for the help!
     

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  20. readymix
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    readymix ...Lest ye be trod upon... Staff Member

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    Nice work! I know AutoZone sells vacuum line tee fittings that should work fine for replacing that guy. Plus now you can move the fitting further from the turbo like you said. :thumbup:
     
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