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1-2-3??? No. More like 1-2-1-2-1-2-3

This is a discussion on 1-2-3??? No. More like 1-2-1-2-1-2-3 within the Automatic Transmission forums, part of the Drivetrain category; I took my 01 Z28 to the track Friday. It has a LS6 with LT's, full exhaust and 241 heads ...

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    Junior Member Z28dryva's Avatar
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    1-2-3??? No. More like 1-2-1-2-1-2-3

    I took my 01 Z28 to the track Friday. It has a LS6 with LT's, full exhaust and 241 heads and a few other things so it's pushing about 360hp. The tranny is either built or has a shift kit but I bought it that way so I'm not sure. I added a cooler about a year ago but I have never raced it. Anyways... I ran it in OD the first time and it took off in first and immediately shifted to 2nd then dropped back into first and shifted like normal from there. It ran 13.5 and should have ran around 13.0-12.8. I decided to manually shift it the second time. It took off in 1st (shifter in first the whole time) it shifted to 2nd immediately just like before and shifted back to 1st. It then shifted BACK to second when it was at around 3500rpm. It then went BACK to 1st and I gave up at that point and just stuck it back in OD. It ran a 13.9 that time.

    My tuner says it's supposed to be able to down shift back to second at any speed below 62mph but it won't shift down on it's own till about 55mph. If I manually shift it down, it will usually run up to 4500rpm then act like it's in neutral. It won't hit 3rd unless I let off the gas.

    Also, I have noticed that if I take off in water or some condition where the tires spin and it has to shift quickly, the transmission seems to get it in a bind and bogs the engine down untill I let off the gas. It does it in some low speed downshift conditions as well.

    I intend to 6 speed swap it in the near future but I don't have the time or money at the moment. I would like some idea of what is going on with this thing for the remainder of it's time as an auto.

    Almost forgot, my tuner ran it several times on the dyno in the quarter mile mode and never had an issue. It makes me think something is loose in the tranny and it only screws up when a sudden take off makes whatever move inside the tranny. Acceleration inertia could be causing it.
    Last edited by Z28dryva; 08-25-2013 at 09:33 PM.

  2. #2
    Spaz is My Mentor SMWS6TA's Avatar
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    So you have TCS/ on?

    Are you still running the OEM stall? How many miles?


    Did your tuner change your shift points in the tune?

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    Junior Member Z28dryva's Avatar
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    01 Z28, 05 Z71

    I don't have traction control. The converter is factory stall speed and I have no idea the miles because it was in the car when I got it. All shift points have been changed to 5900 @ WOT

  4. #4
    Junior Member Z28dryva's Avatar
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    Guess I'll just buy one of these cheap built ones I've seen for sale locally. It will last me till I get my 6 speed setup and rear end

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    Junior Member tekkauto's Avatar
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    Are you still having the problem? Don't over think it. Use a good scan tool and watch your tps voltage and % while you slowly press and depress the throttle if you haven't done so already. There could be a dead spot in the throttle electronics. I work on gm and Chrysler products and its a common diagnostic procedure on the mops but not on the gms. One of my gm techs laughed at me once when I suggested doing this. I proved him wrong.

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    Junior Member Z28dryva's Avatar
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    01 Z28, 05 Z71

    Quote Originally Posted by tekkauto View Post
    Are you still having the problem? Don't over think it. Use a good scan tool and watch your tps voltage and % while you slowly press and depress the throttle if you haven't done so already. There could be a dead spot in the throttle electronics. I work on gm and Chrysler products and its a common diagnostic procedure on the mops but not on the gms. One of my gm techs laughed at me once when I suggested doing this. I proved him wrong.
    I do have an aftermarket throttle body that might have broke the TPS but I don't see it making the tranny shift to 2nd when the shifter is in 1st. My 05 Z71 will do that but it's a little more stuck into the electronic override system things seem to be going to these days and even then, you have to push it to almost 4000rpm at very light throttle to make it force an upshift. I've never had an F body that would shift out of the gear the shifter was in. It would go to the rev limiter and all the way back down to idle before it would up and decide to upshift on it's own.

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    Junior Member Z28dryva's Avatar
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    01 Z28, 05 Z71

    I haven't been on it a while because I've been dealing with other things. I have figured out that the TPS on the car is fine. I tested it with my scanner and even tried another one and it still has the same problem. I did however figure some things out

    When and if it decides to randomly shift to second, it does so tight at peak acceleration when the momentum shift is greatest. Also, if you try to do a donut or try to power slide the car, it will do it without fail every time when the momentum shifts. I don't see how but there HAS to be something loose inside the tranny causing it to shift to second when it moves in the right direction

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    Member RONS98TA's Avatar
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    I would also check all the grounds on the car from the battery to every spot you can find. The battery, frame, and fenders (2). I know I left a few others out. You may have an electronic issue and the f-bodies are know for ground corrosion. Clean them up and give her another test drive.

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    Junior Member Z28dryva's Avatar
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    01 Z28, 05 Z71

    I did an extensive ground cleaning when I put the engine in it back in March. It had the problem before and after the engine swap

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