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Thread: Injector offsets keep changing after 'save'

  1. #1
    Fuel Injected!
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    Injector offsets keep changing after 'save'

    Using TunerPro - I go to the voltage offset table and enter in all the data for the appropriate voltages. Click save, save bin, then immediately go to the parameter and check. Everything is different from what I entered. Tried a few times with the same result. I am quite obviously doing something wrong.

    Can someone point me in the right direction?

  2. #2
    Fuel Injected!
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    It's normal, tunerpro will always round the values to the nearest value that can be calculated from raw hex. All the parameters have finite resolution, so rounding is necessary.

  3. #3
    LT1 specialist steveo's Avatar
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    think of it like this.. an 8 bit number only has 256 possible values, so for example if you want to handle numbers from 0-25500 in an 8 bit space, then you only get steps of 100

    tunerpro will let you enter anything, but it can only save in that limited bit space, so when you go back in, it's recalculated (definitely not a design decision i would have made)

    if it was important that the variable was more accurate, they'd use 16 or 32 bit instead (16 bit has 65536 possible values, 32 bit has over 4 million), in this case, offsets just aren't that accurate

    one common mistake is trying to enter msec offsets into a usec table or vise versa, which certainly would round off into garbage, so make sure you're using the right units of measure

  4. #4
    Fuel Injected!
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    Thanks for the info. I was banging my head against the wall trying to figure out what I was doing wrong. LOL.

    I have the TrickFlow 30# injectors which are a copy/rebadge of the Accel's (I think...) I was able to get the voltage offset info from Accel, and then created the missing data points using a spline. Now that y'all have addressed the question above, the next thing to sort out is the "voltage offset adder" in TunerPro.

    I've read elsewhere to zero-out this table. Any truth to that?

  5. #5

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