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Thread: Add PID: VSS raw pulses per frame?

  1. #1
    Senior Tuner
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    Add PID: VSS raw pulses per frame?

    I would like to have a higher-precision speed
    value, or better yet the delta-X pulse count
    per "tick" from the vehicle speed sensor, to do
    some delivered-HP / delivered-TQ at-the-wheels
    calcs / charts. I don't see the VSS as a selectable
    PID. Could you add this to the next Logger update?

  2. #2

    Re: Add PID: VSS raw pulses per frame?

    VSS is already in the scanner (Speedometer->Vehicle Speed) at the bottom.

    You can't log the VSS pulses directly via a PID (well you actually can using direct memory access scanning but thats another story - stay tuned). The sample time of the ODB2 port is waaayyy too long compared to the TPU sample time, the VSS pulse counter is only 8bits.

    edit: just realised you were after a higher reolution speed signal : direct memory scanning techniques are the only way. The VSS PID is only accurate to 1km/h so you can squeeze a little more out by logging in km/h.






    I count sheep in hex...

  3. #3
    Senior Tuner
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    Re: Add PID: VSS raw pulses per frame?

    Right; I looked at the MPH and couldn't find a way
    to get more (any) decimal places out of it (other
    than .00). I seem to recall seeing something in my
    EFILive that was VSS related. I will have to go look
    at what they have available to choose from.

    Is there an option to get a less-truncated or less-
    smoothed MPH / kph output from the PCM? Or some
    way to get the PCM to accumulate past 8 bits using
    custom PIDs etc.?

  4. #4

    Re: Add PID: VSS raw pulses per frame?

    the MPH the VCM reports in the VSS PID is not smoothed, just the resolution is 1 km/h.

    We can pull a very hi-res VSS speed from the VCM using direct memory scanning, but that has to be customised for each Operating System and is not available yet.




    I count sheep in hex...

  5. #5
    Advanced Tuner TiredGXP's Avatar
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    Jun 2007
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    Sherwood Park, AB
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    Wow, old thread, but I'm going to resurrect it anyway.

    Any chance we'll ever see a higher resolution VSS PID?

    **EDIT - nevermind, transmission output shaft RPM and some basic math will give me what I want.**

    Last edited by TiredGXP; 03-23-2008 at 12:09 PM.
    2005 Grand Prix GXP - 5.3 LS4 - HP Tuned, MF catback, 1.8 rockers, K&N, Some day I'll finish putting the LS6 intake on