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Idle Surge Posible Cause

Posted by a7xinsane, Nov 6, 2019

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  1. a7xinsane

    a7xinsane Proven Member

    Joined Oct 5, 2013
    clarence, Pennsylvania
    Hey guys. So ive been having some real trouble with idle surge over the past month or 2. I followed terrys idle surge guide to a T and still had found nothing so I post this in hopes it may help someone... I had tried everything except a full fiav block off. IAC, TPS, wiring, etc... So finally i sent my throttle body off to throttlebodies.com to be rebuilt to remove any doubt of a bad fiav or plate or what have you... Well after it got back to me I was still having the exact same issues. Hell i even tried switching to speed density to see if it had an effect and it did not. So after another month of trying everything 20 more times i finally said screw it and popped the freeze plug off the back of the throttle body. I saw nothing out of the norm at first but when i rotated the black plastic screw in it began to separate at the middle... My fiav valve had cracked down the center perfectly. It was so fine a crack i cant blame the builder for missing it. But just be aware that this may be the issue plaguing you if you have tried everything but replacing a fiav. Also a warning to others that if you send your throttle body out to be rebuild your builder(or even you) will probably miss this.

    Attached Files:

  2. motomattx

    motomattx Proven Member

    Joined Dec 9, 2010
    wampum, Pennsylvania
    That almost looks like its supposed to be that way.

    Drag Race Build 4K  24

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
    a7xinsane likes this.
  3. a7xinsane

    a7xinsane Proven Member

    Joined Oct 5, 2013
    clarence, Pennsylvania
    Yup it was such a fine crack I couldnt even see it before i started turning the valve. Thats why i made this post.
  4. Steve92talon

    Steve92talon Proven Member

    Joined Jul 3, 2019
    Fernie, BC, Canada
    Turn it all the way in so it bottoms out and seal up the plug with a bit of rtv around the plug and put it back on. My car cold starts at 1500rpm and 800 hot idling. No surge at all that coolant cold start thing is junk.

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