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Thread: Why are my shifts so hard while in Speed Density?

  1. #1
    HP Tuners Support
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    Bill@HPTuners's Avatar
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    Why are my shifts so hard while in Speed Density?

    Many earlier Gen 3 calibrations commanded max line pressure when the maf fails...probably GM's way of telling you to bring your vehicle in to be fixed

    You can disable this function by going into the editor & under Trans Diagnostics change the MAF Max line pressure drop downs to disabled.

    I've attached a picture of the 3 drop downs I speak of.
    It doesn't have to be perfect, it just needs to be done in two weeks...

    A wise man once said "google it"

  2. #2
    Not A Tuner
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    I wonder how mine is set as I didn't notice hard shifts in Open Loop.

    ......you don't mean that little kick in the pants in the 1-2 shift ??


    DH

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  3. #3
    Senior Tuner Russ K's Avatar
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    The 2001 & up vehicles don't have the Maf DTC shift pressure table enabled.

    Russ Kemp

  4. #4
    Advanced Tuner xonelith's Avatar
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    Is this the same thing for us V6's (otherwise known as 'safe mode')? I know if the MAF or the MAP are disconnected, the transmission kinda does the bucking bronco when putting it in D, and shifts really frickin hard.

    If so, I see a request going in to HPT for new parameters
    All Motor 2001 GA GT1




  5. #5
    Tuner in Training
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    Thanks

    Quote Originally Posted by Bill@HPTuners View Post
    Many earlier Gen 3 calibrations commanded max line pressure when the maf fails...probably GM's way of telling you to bring your vehicle in to be fixed

    You can disable this function by going into the editor & under Trans Diagnostics change the MAF Max line pressure drop downs to disabled.

    I've attached a picture of the 3 drop downs I speak of.
    This has been a problem I could not figure out thanks this helps.

  6. #6
    Advanced Tuner MikeGyver's Avatar
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    Quote Originally Posted by Russ K View Post
    The 2001 & up vehicles don't have the Maf DTC shift pressure table enabled.

    Russ Kemp
    I just happened across this thread this morning. My 2002 OS truck had the MAF DTC max shift pressure enabled. It seems like it's been 10 years shifting this way. I haven't been looking for a cure, I just assumed that for some reason the trans shifts like this because of the blower. I figured that I would dig into it some day. I drove out of my way today enjoying how stock-like my trans is now. Maybe it would have caught my eye earlier if in the READ ME section the title was changed from "Max line pressure in speed density" to "Max shift pressure in speed density".
    2000 GMC 2500 2-bar SD
    Stock LM7, LTs, TBSS intake manifold

  7. #7
    Tuner in Training
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    My 2003 truck does not have the MAF DTC max shift pressure enabled. Is there any other way to disable the max pressure shifts?

  8. #8
    Potential Tuner
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    Quote Originally Posted by Russ K View Post
    The 2001 & up vehicles don't have the Maf DTC shift pressure table enabled.

    Russ Kemp
    is there a way to get this enabled? lots of people could use it.

  9. #9
    Tuning Addict blindsquirrel's Avatar
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    Quote Originally Posted by Meangreen View Post
    is there a way to get this enabled? lots of people could use it.
    You're quoting a post from 14 years ago. Lots of stuff has changed, lots of tables have been added over the years. And you are asking a specific question about a specific item in your specific tune file from your specific vehicle, and did not post said file for anyone else to look at to see if they can find something that you overlooked or misunderstood.

  10. #10
    Potential Tuner
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    Goto trans diagnotics and disable max line pressure when maf failed