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Thread: 2007 Silverado L76/4l70e Lazy Shifts.

  1. #1
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    2007 Silverado L76/4l70e Lazy Shifts.

    My truck is completely stock. The only thing I've changed on the tune is turning off DOD and unchecking the box for a cat efficiency code so it won't set a CEL. I'm getting some lazy shifts that I'd like to firm up. Anyone willing to take a look at things for me? Obviously I know your time isn't free. I'll upload the tune shortly. Thanks

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    Tune file enclosed!

    Alright here is the tune file. What I really need is the line pressure turned up. It will rev to like 3-4 grand before shifting to second even at light throttle. I think the trans is about to take a dump and I need like 30 days to save up for a rebuild. Thanks in advance.

    2007 Silverado Vortec Max no dod 420 430.hpt

  3. #3
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    Anyone? 🙏🏾

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    Tuning Addict blindsquirrel's Avatar
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    A log with all the trans stuff, most especially Time of Latest Shift, would be really super helpful. If it takes significantly longer to complete a shift than what's asked for in the tune, I don't think there is much you can do to help it live a little longer.

    Have you reset adaptives, in the scanner? Mine used to get confused and drag the 1-2 shift duration out to over 1 second, clearing adaptives would fix it.

  5. #5
    Senior Tuner TheMechanic's Avatar
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    Double your torque reduction in trans tab. That will get you some more time on the trans. It will be a dog on shifting but it will get you more time. Then go back to stock when you do your O/H and tune with BlueCat

  6. #6
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    Adding a log file to the thread!

    translog2.hpl

    Attempted to change some things. The main issue with the first to second shift does seem somewhat better but your expertise would be very helpful. What its doing is it won't shift from first to second without being over 20 mph whereas it didn't do that before. Hell I'd argue it was to eager to get to a higher gear. Now it revs like its trying to hold the gear before a shift. Like a car in sport mode or something. Let me know what you guys think. Thanks

    P.S. The log is kind of long. I didn't know what all you guys needed.

  7. #7
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    Quote Originally Posted by blindsquirrel View Post
    A log with all the trans stuff, most especially Time of Latest Shift, would be really super helpful. If it takes significantly longer to complete a shift than what's asked for in the tune, I don't think there is much you can do to help it live a little longer.

    Have you reset adaptives, in the scanner? Mine used to get confused and drag the 1-2 shift duration out to over 1 second, clearing adaptives would fix it.

  8. #8
    Tuning Addict blindsquirrel's Avatar
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    I think it's smoked.

    Shifts are being commanded on time as normal, but it's commanding 3rd before the trans has even made the 1-2.

    screenshot.04-02-2023 01.53.30.png

  9. #9
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    Ahh okay that makes sense. I was looking at the log as a novice and thought that as well. I'm taking it to the transmission shop in a week or so. Thanks for taking a look at things.

  10. #10
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    I think my bad tuning had something to do with the trans commanding 3rd before the shift. While I'm sure I'll need a trans soon, I think I had the shift rpm and speed to close to the second gear speed and rpm.

  11. #11
    Tuning Addict blindsquirrel's Avatar
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    I don't see that, not unless the tune file you showed was not the one being used when that log was taken.

    My truck is using a smaller MPH spread between gears than yours and it shifts like this, at about the same throttle as the screenshot of yours up above:
    screenshot.10-02-2023 07.01.52.png