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Thread: Gillis not adjusting

  
  1. #31
    OVER-BOOST!! svono50's Avatar
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    I have seen bypass valves leak in the past, where they sometimes leak enough to hinder boost levels. If the bypass leaks, the boost from the turbo leaks right back around into the inlet of the turbo, which is like if one of your intake gaskets blow or one of the hoses blow off. You may also want to cap off the bypass circuit on the intercooler and turbo inlet and see if you get any change in boost response.

    Since your boost is building along with RPM vs running up quickly and leveling off, then you either have a boost leak or your wastegate valve is stuck open allowing exhaust to go around the turbine. Do you still have a stock exhaust elbow on the turbo with the integral wastegate valve or are you running an aftermarket setup?
    Ted
    86 SVO Mustang
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  2. #32
    14 PSI Boost
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    Everything is stock (IHI). I pulled the air source to the wastegate today. Completely eliminated the BV, plugged all vacuum ports and ran the car. This is where I should get insane boost right? (I've never done this before so I think I did it correctly). The result is the same, no greater than 10psi of boost. So if I did this right believe I have a stuck open wastegate? If the wastegate is open all the time it bleeds the boost and will only get what the wastegate spring allows. Is this correct?

  3. #33
    Administrator SVOeric's Avatar
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    We can't be 100% sure, but there's likely nothing wrong with your wastegate, (unless someone has made a hose-less vacuum line)
    if it weren't connected, you'd have ZERO boost. if it were stuck shut, you'd have tons of boost.

    Ted has nailed it, most likely cause is the bypass valve is dumping your boost. plug it, and see what happens.
    Eric C
    SVOCA Webmaster

  4. #34
    14 PSI Boost
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    I seem to be getting contradictory statements which can be a problem when writing in forums. Ted is saying if the wastegate is stuck open it will get the boost to build along the RPM Range slowly which is what the car is doing. Eric is saying "if it weren't connected (assuming he's talking about the wastegate) you'd get no boost". So if I disconnect the vacuum line from the wastegate I will get no boost? I disconnected the vacuum source to the wastegate and got boost (same 10psi). Eric mentioned "if the bypass valve is dumping boost "plug it" and see what happens". Plug it where/how? Plug it where the ball bearing seats inside?

  5. #35
    Administrator SVOeric's Avatar
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    I think a couple things are getting confused.
    so the waste-gate actuator connects to a arm inside the exhaust. That arm controls a flapper valve.
    IF that flapper valve is open, you will never build over ~3 psi of boost.
    IF that flapper valve is stuck closed, you'll build boost til it goes BOOM.
    IF that flapper were stuck, but just barely open, you'd build a bit of boost, but only in the REALLY high RPM range, and really slowly (what Ted was asking about)

    Ted and I are saying, that because you are building boost, and then holding boost at ~10 psi, it sounds like the waste-gate is not stuck, and is working properly. Your last test, you unplugged the wastegate, and left it open to atmosphere, in that setup, the wastegate will never open the flapper valve, and you'll build boost until you let off the gas.
    That only leaves ONE other possibility. your boost is leaking out somewhere else.... most likely culprit is the blow-off valve. the plastic valve hanging off the Intercooler, connected by ~1 inch hose. Those plastic ones aren't all that great anyway.
    You could try unplugging the vac line to it first, but I'd just use a hand clamp, and pinch that 1-inch hose off, and take if for a test-drive.
    Eric C
    SVOCA Webmaster

  6. #36
    OVER-BOOST!! kiwi's Avatar
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    Maybe no "preload" on the WG arm?
    1 Modded, 1 Not

  7. #37
    OVER-BOOST!! svono50's Avatar
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    Eric, re-read post #32...the bypass valve (BV) was eliminated during his test run, if I am reading that correctly. From what all has been explained above by stangesvo, I have to lean toward the flapper valve being held open just enough to only allow 10psi, which is likely above 5000 rpm somewhere. I have had my aftermarket setup stick open enough to know that exact scenario all too well (working on a solution, slowly). If the flapper valve were fully open, it would still allow a small amount of boost, but certainly less than 10psi.

    At this point, you need to dig into that wastegate/flapper valve system and see what is going on. Maybe something happened where there is no longer any preload on the flapper (as Kiwi noted) or the wastegate diaphragm is stuck or something wedged in the flapper. I hate to say it, but it may be best to yank the turbo out so you can better examine it on a bench top rather than still in the car. Personally I would try and diagnose as much as I could in the car, but don't rule out having to yank it.
    Ted
    86 SVO Mustang
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  8. #38
    Administrator SVOeric's Avatar
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    yeah, it didn't specifically say the BPV was blocked off. from the way he worded it, I got the impression he unplugged the vac line to it. maybe I'm reading something into it that's not there.

    If the flapper is open you won't build more than 3 psi at 5k rpm. Trust me, I'm intimately familiar with this scenario. altho he does say this is an IHI turbo, not the T3, small chance it would build more, but I'd be very surprised if it built 10 psi.

    IF the flapper is in question, it's easy to check. Crawl under it, take the C-clip off, and remove the arm from the actuator. Make sure the arm moves freely. When you put it back on, as Kiwi mentioned, make sure there is some tension holding the flapper closed.
    Eric C
    SVOCA Webmaster

  9. #39
    14 PSI Boost
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    Okay thanks for breaking it down barney style. First I will check the Blow-off valve because that's easy (like my sister oooohhhh). Then I will check the wastegate. But I just started my leave so I won't be able to get back to this until the last week of July. So I will take a break and update soon on what I find out . Thanks for the help.

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