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Thread: Reading vehicle speed important on tuning?

  1. #1
    Potential Tuner
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    Oct 2021
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    Reading vehicle speed important on tuning?

    Drivetrain swap in an old truck. Using 05 grand Cherokee 5.7L and 545rfe transmission. using 2007 Durango pcm i have no speed reading on gauge or hp tuners RPM reads great on gauge and hp tuners just no speedometer. Probably a dumb question but Im curious if the speedometer is as important as RPM before i ask if someone could look at the data logs and recommend any changes to make. Thank you.

  2. #2
    Tuner fumanchu182's Avatar
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    Oct 2019
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    RPM, spark, spark correction, inj duty cycle, inj pulswidth, fuel mass cylinder 1, wideband reading and narrowband readings and that 90% of the channels needed for tuning an engine. Is that PCM a ngc3? I'd say try and log throttle torque source but I don't think that pid exists.

    Speed could be important if you were doing something like boost by speed like in a Holley setup but I don't think you are...
    Hellcat PB > ET: 10.092, MPH: 135.650, 60': 1.492, R/T: .000
    Bone Stock Scat Pack PB > ET: 11.612, MPH: 119.52, 60': 1.634, R/T: .000 (gone but not forgotten).

    https://youtube.com/user/fumanchu182

  3. #3
    Advanced Tuner PurpleRam's Avatar
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    Aug 2017
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    Quakertown PA
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    Yes and No, yes because of the relationship between VSS , throttle % and and Tq request...... No, because unless you really dig deep into the Pedal request table and power % table , remember 90% of the end users , one size fits all on those two tables.

    So as long as the trans shifts with out any long over run....ignore everything I just wrote.



    EDIT: What I should say is... 90% out there won't dive deep enough in to the tune to take advantage of what little gain there is to be had,
    Last edited by PurpleRam; 1 Week Ago at 02:19 PM.
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