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Thread: have somebody adjusted or modified shift points in a jeep XJ 4.0 99-01

  1. #1

    have somebody adjusted or modified shift points in a jeep XJ 4.0 99-01

    It is wear that they put the options in the transmission data but it seems like it does not work.
    or what I am doing wrong, have somebody working on that in here.

  2. #2
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    Shift points are probably for the shift light on a manual trans, not an auto. Take a look and see if the tab you're in says "manual".

    PS - there is a whole separate dodge transmission sub-forum.
    Last edited by spoolboy; 2 Weeks Ago at 09:12 AM.
    If in doubt, multiply everything by 1.1.

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    i have tested too, it doesnt changue anything. tried on a 2000 XJ cherokee and 2005 TJ jeep.

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    Quote Originally Posted by castorjames View Post
    i have tested too, it doesnt changue anything. tried on a 2000 XJ cherokee and 2005 TJ jeep.
    You should have been able to modify the shift points on the '05 TJ 42RLE. There is a RPM/TPS scale for the down/up shifts. You have to convert the RPMs to output shaft RPMs. I don't think the pre '05s can be adjusted other than some torque management values.

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    Quote Originally Posted by TJTurbo View Post
    You should have been able to modify the shift points on the '05 TJ 42RLE. There is a RPM/TPS scale for the down/up shifts. You have to convert the RPMs to output shaft RPMs. I don't think the pre '05s can be adjusted other than some torque management values.
    I did and it didnt made any difference, started increasing by small amounts, then i did big changues just for testing.didnt work.
    Attached Files Attached Files

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    Quote Originally Posted by castorjames View Post
    I did and it didnt made any difference, started increasing by small amounts, then i did big changues just for testing.didnt work.
    Hopefully my attachment was a successful and you can do a comparison on the settings. It worked on my '06...the only thing I couldn't get to change was the WOT shift points. I'm thinking instead of raising the 100% TPS/RPM settings I may need to raise the 80% settings some more. I have also attached the RPM shift calculator I made in Excel if anybody needs it.
    Attached Files Attached Files

  7. #7
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    The shift points are in fact adjustable as TJTurbo stated. Keep in mind the rpm scale is driveshaft output shaft speed and not engine rpm. TJ's spreadsheet converts this nicely for you. This is a rare instance where you also want to log TPS % instead of throttle voltage ( I don't understand why we can't just stick with one or the other with Jeep!) so you can understand when the shifts are occurring and what changes are made.

    TJTurbo I owe you a PM response from way back! Haven't been on much but I'll reply in case you still need it.

  8. #8
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    i was talking WOT shift points, i couldnt make it work.. i used some crazy number and no no

  9. #9
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    Hopefully one of us will get the WOT shifts figured out. The 4-3 downshift was my biggest gripe about the factory shift schedule. My turbo would build boost when going up long grades with nowhere to go creating high IAT's/EGTs unless I darn near floored it to get the downshift. Now I'm getting the downshift closer to part throttle with much better driveability.