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Thread: TPS correction from datalogs

  1. #1
    Potential Tuner
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    TPS correction from datalogs

    I have used the app on some track sessions and found that my TPS logged position is off, it reads about 9% when closed and maxes to 90% when open
    Searching the forums I found this is due the fact sensor TPS works, as it reads around 0.5v when closed and 4.5 or so when open, thus no correlating

    question is, is there any easy fix/workaround for when you load this data into racerender? because the TPS gauge is really awkward and didnt found an easy way to fix the values.

    Thanks a lot for the help in advance.

  2. #2
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    anyone ?

  3. #3
    Potential Tuner
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    You can use the calculated field option to adjust the value based on a formula. Would that work?

  4. #4
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    I was wondering to use it, but wasn't able to figure out which formula could correct this, as the value that gets recorded is the actual percentage, not the raw voltage
    I was hoping that there were more ppl experiencing the same issue, but maybe I should ask racerender instead

  5. #5
    HPT Employee Weston@HPTuners's Avatar
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    The root cause of this is the way that the OBD-II standard is defined... PID 0x11 gives us the throttle position as a percentage, based on a voltage between 0 and 5 volts, even though most TPS sensors have a range closer to 0.5 - 4.5V, so it's pretty rare to see a car that will report it as 0-100%... Most seem to be from about 9-13% to 87-91%. Of course they're all just a little different, so that hinders the idea of some universal solution to clean this up.

    There are a few things we can do to help with this:

    1) On some vehicles, there *may* be alternate throttle position data channels available, which could also have some different characteristics. There may also be a throttle pedal position option, which is probably what you want if you're trying to log driver inputs.

    2) In TrackAddict's video overlay setup screen, tap on the "Throttle" box and select "Throttle (auto range)"... this will adapt the throttle display to fit the actual data range that has been observed in your recorded session. The downside is that if you never hit zero throttle or 100% throttle, it's going to make it look like you did.

    3) In RaceRender, the properties box for most data displays will give you the option to set a specific data range, or you can simply un-check those boxes to put it into Auto mode, which will adapt it to the actual observed data range, just like option #2 above.


    As for displaying the number adjusted to be 0-100%, that gets a bit more tricky... The Calculated Fields in RaceRender are only setup to apply just one arithimetic operation to a data channel, and we really need two here. So in this case, you'd have to either edit it in a spreadsheet program to add your own calculated data column, or program a custom display via Script Editor available for Enhanced Display Objects.

  6. #6
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    Thank you very much for your detailed reply, that does make sense and is what i was expecting, but unfortunately if i leave RaceRender adjust the min/max reading then it wont match the 0/100% legend, its not that critical but if you have a full swipe gauge it will only stick at 9% - 90% as described, one way would be just to hide the values, but still looks awkward i guess. It doesn't look good to see the TPS at 90% or so when you are in full throttle or even 9% when you are breaking, hehe.

    Just out of curiosity, what would be the formula/ arithmetic operation to get this fixed, i can use the last recommendation of fixing it externally within the CSV values themselves.