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Thread: Can't get calculated PID to work for MPG

  1. #1
    Senior Member PSWired's Avatar
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    Default Can't get calculated PID to work for MPG

    Hi folks, trying to create a calculated PID to give an MPG readout in the scan tool. Problem is that the PID won't show up in the "Data" tab even when selected on the PID selection tab. The PID is set to multiply lb/hr of airflow by the current AFR to get lb/hr of fuel, then convert lb of gasoline to gallons of gasoline to get gallons/hr of gasoline. Multiplying the vehicle speed in MPH by the inverse of GPH gives the final MPG readout. Here's the contents of my calc_pids.txt file:

    # ================================================== ============================
    # File details
    # ------------
    #
    # This section defines various details about the file format.

    *FILE

    #Parameter Value Description
    #---------- ---------------- ---------------------------------------------------
    VERSION 7.1.1 File version
    DECSEP . Decimal separator used in this file


    # ================================================== ============================
    # Units
    # -------------------
    # See sae_generic.txt for more information on the *UNITS section

    *UNITS

    #Code System Abbr Description
    #-------- ---------- -------- -------------------------------------------------------------
    #None None "" "No units"

    mpg Imperial mpg "Miles travelled per gallon of fuel"


    # ================================================== ============================
    # Add slot definitions here
    # --------------------------------
    # See sae_generic.txt for more information on "SLOT" formats
    #
    #Units Low High Fmt Expression
    #------------ ------------- ------------- ---- --------------------------------------------------------------

    *CLC-00-001
    mpg 0.0 100.0 0.2 "(1/({SAE.MAF.lbpm}*(60)*(1/{GM.AFR})*(1/42.5)*(7.4805)))*{SAE.VSS.mph}"


    # ================================================== ============================
    *PRN - Parameter Reference Numbers
    # --------------------------------
    # See sae_generic.txt for more information on the *PRN section
    #
    #Code PRN SLOT Units System Description
    #------------------------- ---- ------------ ---------------- ---------------- ------------------------------------------

    CALC.MPG F600 CLC-00-001 "mpg" Fuel "Miles per gallon"
    1995 GMC Yukon 4WD 4DR
    5.3 "LMG" engine: E85 with AFM
    6L80e 6 speed automatic transmission

  2. #2
    Lifetime Member
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    try this it worked for me

    (1/({SAE.MAF.lbpm}*60*(1/{GM.AFR})*(1/42.5)*(7.4805))*{SAE.VSS.mph}
    EFILive - The Single version of the Truth

    Larry - HumpinSS

  3. #3
    Senior Member PSWired's Avatar
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    Doesn't look like that worked. The PID isn't even showing up in the "Data" tab when it's selected. BTW, I'm using v 7.2.3 pre release 002 (build 246).
    1995 GMC Yukon 4WD 4DR
    5.3 "LMG" engine: E85 with AFM
    6L80e 6 speed automatic transmission

  4. #4
    Joe (Moderator) joecar's Avatar
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    On the Data tab display, click on the "System" column (to sort by System) and see if it shows up.

  5. #5
    Senior Member PSWired's Avatar
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    I don't have a system column on my Data tab section. I sorted by another column and it didn't show up. When I select another PID it shows up just fine.
    1995 GMC Yukon 4WD 4DR
    5.3 "LMG" engine: E85 with AFM
    6L80e 6 speed automatic transmission

  6. #6
    Lifetime Member TAQuickness's Avatar
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    Default Re: Can't get calculated PID to work for MPG

    Quote Originally Posted by PSWired

    CALC.MPG F600 CLC-00-001 "mpg" Fuel "Miles per gallon"
    2 things.

    Change F600 to F001

    Take the quotes off mpg


  7. #7
    Senior Member PSWired's Avatar
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    Okay, made those changes and still not getting the PID showing in the Data section. One other thing I noticed- the description of the PID in the PID tab is "Miles per gall" instead of "Miles per gallon" if that means anything.
    1995 GMC Yukon 4WD 4DR
    5.3 "LMG" engine: E85 with AFM
    6L80e 6 speed automatic transmission

  8. #8
    Lifetime Member TAQuickness's Avatar
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    Quote Originally Posted by PSWired
    Okay, made those changes and still not getting the PID showing in the Data section. One other thing I noticed- the description of the PID in the PID tab is "Miles per gall" instead of "Miles per gallon" if that means anything.
    you need a caraige return after the last line

    have you logged any data yet?


  9. #9
    Joe (Moderator) joecar's Avatar
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    PSwired,

    You're right: I see the CALC.MPG pid under the "PIDs" tab but not under the "Data" tab.

    Under the PIDs tab though, I see the description as "Miles per gallon".

    I can log data on this pid;

    My other calculated pids in calc_pids.txt show up under the Data tab; these have a PRN ranging from F060 to F070.

    (BTW: what are these constants 42.5 and 7.4805...?)

  10. #10
    Joe (Moderator) joecar's Avatar
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    Hmmm... I tried moving stuff around in calc_pids.txt (quotes, spaces, fields, CLC-00-XX, FXXX, etc...) and it still doesn't show up under the Data tab; but my other calculated pids do.

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