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Thread: Auto 4T45 Lag When Launching

  1. #1
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    Auto 4T45 Lag When Launching

    A little background info. I have a 2.4 LE5 cobalt. I supercharged it 5 months ago, and ever since then I've had this lag when I hit the throttle from a dead stop. The car kind of bogs and leans out and then after a second or two it will take off.

    My tuner doesn't exactly know why, but he has found a way to make it so the lag isn't so bad. But it is still there, and he says for some reason it's limiting the throttle body from opening all the way when I floor it. I think he said it's only opening 80% or something. Any idea why it bogs?

    Also, at a dead stop and I hold the break, I can only rev up to 1750 rpm. How do you get rid of that so I can rev it up a little higher and get a harder launch?

  2. #2
    Quote Originally Posted by scottyguy401 View Post
    A little background info. I have a 2.4 LE5 cobalt. I supercharged it 5 months ago, and ever since then I've had this lag when I hit the throttle from a dead stop. The car kind of bogs and leans out and then after a second or two it will take off.

    My tuner doesn't exactly know why, but he has found a way to make it so the lag isn't so bad. But it is still there, and he says for some reason it's limiting the throttle body from opening all the way when I floor it. I think he said it's only opening 80% or something. Any idea why it bogs?

    Also, at a dead stop and I hold the break, I can only rev up to 1750 rpm. How do you get rid of that so I can rev it up a little higher and get a harder launch?
    Replace your factory airbox with an open element air filter.

    Buy a higher stall TQ converter.

  3. #3
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    Quote Originally Posted by Andy0x1 View Post
    Replace your factory airbox with an open element air filter.

    Buy a higher stall TQ converter.
    I have a k&n intake, is the stall tq converter the reason why I can't rev up higher than 1750 rpms and why it bogs trying to launch?

  4. #4
    Tuner in Training AleroB888's Avatar
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    Quote Originally Posted by scottyguy401 View Post
    I have a k&n intake, is the stall tq converter the reason why I can't rev up higher than 1750 rpms and why it bogs trying to launch?
    Any black smoke out the exhaust when you blip the throttle? I'm asking because if I try to use a larger injector than 28 lbs, there is no way to keep the plugs from fouling, no matter where you set the IFR. That's the only table supported in my engine's calibration....

    If it's not that, I have a suggestion if you are using an Eaton Supercharger....
    1999 GLS MP90 supercharged / 2003 GL MP62 supercharged / 2004 GLS stock
    Magnuson MP90 / TOG's / 3 in. Magnaflow exhaust / MSD ignition / LS1 MAF / Racetronix pump / HP Tuners / TCE 68mm TB / 36 lb Inj
    = Best track time: 12.951 @ 104.48, 1.839 60 ft. (Beech Bend Raceway Park, 11-23-13), 50 Deg. F
    http://www.youtube.com/watch?v=hpVYZPbpPzk

  5. #5
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    I just replaced the plugs, and it's still lagging. What's your suggestion?