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2G Slow acceleration

Posted by garytheberry, Jul 1, 2020

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  1. garytheberry

    garytheberry Probationary Member

    Joined Jul 1, 2020
    New Braunfels, Texas
    Hey guys, I have a 1999 eclipse gst. I’ve been having this issue where the car will make plenty of boost (the gauge shows that it does and the blowoff valve will engage easily) but the car barely accelerates. By the time I get to third gear I have zero acceleration. The only time this happened before, one of the couplings for the intercooler piping was loose. I’ve looked over every hose and can’t find the issue.
  2. ThunderChild

    ThunderChild Supporting VIP

    Joined Jan 5, 2012
    Rathdrum, Idaho
    BLT, might have a bad gasket somewhere on the throttle body or intake manifold as well.

    Street Build 965  3

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  3. garytheberry

    garytheberry Probationary Member

    Joined Jul 1, 2020
    New Braunfels, Texas
    To expand on the situation, the engine will rev high and make boost but just barely accelerates in first and second gear. By the time I get to third gear I’m at such slow of a speed that the car won’t accelerate at all and won’t rev either.
  4. CAM280

    CAM280 Supporting Member

    Joined Oct 6, 2019
    BRISBANE, Australia
    Are you reving high but going no where? Could be the clutch?
  5. luv2rallye

    luv2rallye DSM Wiseman

    Joined Jun 7, 2003
    Minneapolis, Minnesota

    3K  0

    1999 Mitsubishi Eclipse GST
    14.200 @ 95.000 · 2G DSM
  6. Mello

    Mello Proven Member

    Joined Jul 4, 2003
    Albuquerque, New Mexico
    Sounds like you have a boost leak. As @ThunderChild said, do a BLT. The boost gauge doesn't measure boost, it calculates it through the ECU's MAF & RPM data. Your probably sucking in a lot of air at high RPM's & blowing it out a large leak. IE: it's not a real boost gauge.
    Last edited: Jul 2, 2020
  7. motomattx

    motomattx Proven Member

    Joined Dec 9, 2010
    wampum, Pennsylvania
    Check also for a clogged catalytic converter and check that the timing marks all line up properly.

    Drag Race Build 4K  10  24

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
  8. garytheberry

    garytheberry Probationary Member

    Joined Jul 1, 2020
    New Braunfels, Texas
    I know it’s not a real boost gauge. Ive seen it where you can make a fitting that clamps on to the tubing just before the turbo and hook up an air compressor to it, I might try that
  9. pauleyman

    pauleyman DSM Wiseman

    Joined Nov 19, 2011
    oklahoma city, Oklahoma
    We are implying you must try that. It's called a boost leak test as stated above or BLT. It's very difficult to spot leaks otherwise. Any leaks the computer won't know and just happily injects enough fuel for the air it thinks is there but isn't.

    Street Build 3K  1

    1997 Eagle Talon TSi AWD
    awd · manual · 2G DSM
    19Eclipse90 likes this.

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