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This is a discussion on Boost surge/BCS within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; My money is still on your vaccuum lines. Unless something drastic happened with the turbo (bent fins, and the like) ...

  1. #16
    Good news, everyone! xxxxxxxAnub1s's Avatar
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    My money is still on your vaccuum lines. Unless something drastic happened with the turbo (bent fins, and the like) I don't see why your wastegate would just all of a sudden need adjusting. And if something did happen to the turbo, wastegate adjustment won't solve the issue.
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  3. #17
    Registered User wrx wagone's Avatar
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    I had the same problem and it was the stock BCS. It likely got some gunk in it and the response is slow. They're easy to swap. See if you can swap one from a buddies car.

    I also have a new one in a box I'd sell you for $50.
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  4. #18
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    My money is still on your vaccuum lines.
    Yeah I'm going to replace the cracked one today. The one I bought over the weekend was too wide for the existing fittings.

    I also have a new one in a box I'd sell you for $50.
    Good to know. I'm seeing used ones on ebay for about $30, so I'll probably go that route for now, but I'll keep it in mind.

    Thanks for all the help, I'll post back after I replace the vacuum line... maybe my ghetto tape job just wasn't enough.

  5. #19
    Registered User teflon_jones's Avatar
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    My money is still on the vacuum lines too.
    Scott
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  6. #20
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    Well, I replaced the main line (coming from BCS to T fitting) and it feels a little better than how it last felt. Friend from work didn't notice, but I could definitely still feel a slight surging. Although, it was not nearly as bad as in the beginning.

    The new vacuum line, has a much smaller inner diameter than the cracked line that I removed. Could the smaller diameter effect boost? That's more of a side question.

    I went ahead and bought a new (read: used) BCS off of ebay today, so I'm not going to rush to any conclusions until I swap that in. If you guys can think of anything else, let me know. I'm going to replace each of the 3 vacuum lines after work today just to be safe.

  7. #21
    Registered User teflon_jones's Avatar
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    Yes, the smaller line can make a difference. It's a pressure-based line, which means the smaller line will flow less fluid and not work quite the same.

    Is it going to cause a problem, or is it the cause of your continued troubles? That's impossible to say without knowing the exact difference in size versus the previous line.
    Scott
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  8. #22
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    The difference is a full 1/16 of an inch. Old line is 3/16 new line is 2/16. Is that too small??

  9. #23
    Registered User jd92677's Avatar
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    Quote Originally Posted by maw230 View Post
    The difference is a full 1/16 of an inch. Old line is 3/16 new line is 2/16. Is that too small??
    I would replace it with an equal diameter line, just to be sure, but I'm not sure if it would make a difference.
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  10. #24
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    Yeah. Maybe a hardware store would have more of a selection than the local auto parts store.

  11. #25
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    Ok, so after removing the t fitting I noticed that the end that sends air to the wastegate has a tiny brass restrictor installed in the tip. Is that normal?

  12. #26
    Registered User teflon_jones's Avatar
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    Yes it's called a restrictor pill.

    That difference in inside diameters shouldn't make a difference, but it could. I'd get the right size hose before going any further. It's a cheap part and easy to replace.
    Scott
    Past Subies - '11 STI Limited stage 1+ and '04 STi stage 2+
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    '77 F-150 heavily modded for off-roading

  13. #27
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    Yes, I think you're right. I might as well get the same size hose that was on there before. The BCS solenoid should arrive in a few days. Here's to hoping it works!

  14. #28
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    As it turns out, I bought the same size hose all along, it just looked larger on the ends, because it had been stretched out.

    I installed the new (used) BCS this morning, took it for a drive, and noticed absolutely no difference. Still surging. So, either this BCS is defective as well (not likely) or the problem lies elsewhere...

    Should the next step be to install a boost gauge? Or adjust the wastegate actuator arm more?

  15. #29
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    Still clueless here, any help would be great.

  16. #30
    Moderator Donkey's Avatar
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    Yes get a gauge and try to adjust the wastegate arm again................
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