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Thread: 4l80e change gear completely opposite to what it should

  1. #11
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    After testing something more, it turns out that after running about 1.5 miles, the gearbox works just fine.
    Tried to just turn off the ignition and then start the engine right after then it works fine, but after stopping for 5 minutes to fill the tank then it has to run for 1.5 miles before it works right again.
    97 Chevy RCSB 4WD, Internally stock 350 ,stock PCM, 4l60e, Bassani headers catback
    72 Firebird Formula ,engine 70mod 400 Ram air 3 ,0411 Road Runner PCM program Lextech, Lc-2 ,4l80e , axel9"wavetrack 3.91 ,Front rear brakes from gen5. Camaro,

  2. #12
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    the reason for 4l80e switching quickly up to 4 gears ,was that the connection C2 16 and 19 on the PCM were grounded.
    so that PCM received signal that 4wd low range was enabled and front axle was engaged.
    97 Chevy RCSB 4WD, Internally stock 350 ,stock PCM, 4l60e, Bassani headers catback
    72 Firebird Formula ,engine 70mod 400 Ram air 3 ,0411 Road Runner PCM program Lextech, Lc-2 ,4l80e , axel9"wavetrack 3.91 ,Front rear brakes from gen5. Camaro,

  3. #13
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by Ponrov View Post
    After testing something more, it turns out that after running about 1.5 miles, the gearbox works just fine.
    Tried to just turn off the ignition and then start the engine right after then it works fine, but after stopping for 5 minutes to fill the tank then it has to run for 1.5 miles before it works right again.
    Odd... I don't see how 1.5 miles factors into anything.

  4. #14
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by Ponrov View Post
    the reason for 4l80e switching quickly up to 4 gears ,was that the connection C2 16 and 19 on the PCM were grounded.
    so that PCM received signal that 4wd low range was enabled and front axle was engaged.
    That explains it... at street speeds in 4wd-lo you would be hitting the shift curves very soon, good job on finding it.

  5. #15
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    I use this program to program the 4l80e this was very nice to use , now it shift very smooth " https://forum.efilive.com/showthread.php?5876-Tool-to-help-tune-A4-shift-points"
    Now it`s time to try to Calc.VET: correcting MAF and calculating VE (in single log) .
    Br Ponrov
    97 Chevy RCSB 4WD, Internally stock 350 ,stock PCM, 4l60e, Bassani headers catback
    72 Firebird Formula ,engine 70mod 400 Ram air 3 ,0411 Road Runner PCM program Lextech, Lc-2 ,4l80e , axel9"wavetrack 3.91 ,Front rear brakes from gen5. Camaro,

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