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Thread: Jeep 42RLE question...

  1. #1
    Tuner in Training
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    Sep 2019
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    Jeep 42RLE question...

    Can someone please explain to me why does raising the RPM on the 4-3 downshift initiate the shift sooner with a lower throttle position? It seems that logically you would lower the RPM but that's not the case. What am I not understanding here? 😁

  2. #2
    Banned
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    It?s the threshold at which downshift occurs. If you raise the rpms at which downshift occurs the sooner it will hit that threshold to command downshift. The rpm doesn?t go to zero when you coast and count upwards towards the rpm target, it goes down from whatever it is at when you let off the throttle towards the threshold. Or, if you raise rpm to a point where you give it more throttle and your actual rpm is below the threshold of the new throttle position it will command a downshift. And of course rpms is output shaft speed.

  3. #3
    Tuner in Training
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    Sep 2019
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    Got it now, thanks. I made an Excel spreadsheet that converts the output shaft RPMs to engine RPMs for each transmission gear ratio. Now I can better visualize what the changes will do before I make them.