Turbo acting up... Problem???
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This is a discussion on Turbo acting up... Problem??? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I was just wondering if anyone knows what the problem can be.... Driving in 5th gear accelerating into the 2500 ...

  1. #1
    Registered User AsILayDying's Avatar
    Join Date
    Dec 2008
    Central Florida

    Turbo acting up... Problem???

    I was just wondering if anyone knows what the problem can be....
    Driving in 5th gear accelerating into the 2500 to 4500 rpm area I feel the power or boost fluctuate on and off. I can even hear it, like the boost is spooling for a second then off and back on and then off. Is this a symptom that my turbo is starting to fail?

    I still hit target boost levels at 16.7 psi, and I only have this issue in 5th gear. All other gears seem to boost properly straight through until shift or lifting foot off. Any help would be appreciated. Thanks.
    BlobEye Syndicate #-666
    Stage II 04' WRX Black (Performance Race Solutions Tuned 310whp)
    "its never enough"

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  3. #2
    Moderator Donkey's Avatar
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    Apr 2005
    Da boonies,Va
    I Support ClubWRX
    Well are you saying you know the boost is fluctuating? I assume you have a boost gauge if you know your hitting target boost. You might just be getting boost osculations. Most maps target 3rd gear for max boost. Boost is load/gear dependent so you generally will overboost in 4th and 5th and the ECU tries to fix that. Are you still using the factory BCS?
    Resident Adviser @ WTF Tuning, LLC
    2002 FORESTER S
    1998 FORESTER S

  4. #3
    Registered User JUSTINSNUTSWINGER's Avatar
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    Jul 2008
    San Antonio
    ^ What he said... mine did the same thing till I got a 3port and tuned. I have one 4sale BTW. PM me for details.

    2000 Escort

    Maintenance schedule and poke in the eyes:

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  6. #4
    Registered User Sarra's Avatar
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    Aug 2008
    Dreadford, OR
    Not sure on the 04+, or the STi, but the 2002/2003 has horrible mapping for boost, WGDC, and even timing is pretty bad. Example is, at part throttle, there's an actual dip in the boost target table, AND in the WGDC table, so boost would literally go from 6 PSI to 4 PSI and back up to 6 PSI.

    At WOT, my stock tune was a little off as well. It would spool the turbo up to wastegate boost by about 2,250 RPM, and then the BCS wouldn't really do anytihng until higher in the RPM band. I've tuned this all out of my car now.

    The one thing that came to mind would be a possibility of the wastegate arm being out of adjustment. I know mine was, I couldn't hit target boost, even if the boost target was 40 PSI and the WGDC was 96% solid everywhere, it would hit 12.3 PSI and stay there until I let off. Maybe talk to a local tuner about this, they might have specific knowledge on this issue and a fix for it.

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