Hello,
I was wondering what value the channel ecu.usedfuel is outputting to make the virtual fuel tank work? Is that a positive or negative value, is it in liter, with decimals?
Why do I ask? I’m running a different ECU with the ADU and I do all timing related stuff with the ADU and I wanted to make the virtuel fuel tank work to get the fuel per lap. But to make that work, I need to know what value is output via the ecu.usedfuel channel.
Thanks a lot community.
Claude
It is used fuel in litres with two decimal places. So a raw value of 100 means 1.00 L.
Ok, thanks a lot.
And what is the behavior of that value? Is that value zeroed out at every ecu restart, or is it a number that continously gets bigger?
In other words how does the ADU handle that number? is the virtual fuel tank using the raw value, or is the ADU calculating a Delta that is than substracted from the valued of the virtual fuel tank?
Claude
It depends on your ECU. On Ecumaster ECUs it is reset after an ECU restart. I believe this is also the case for other manufacturers.
ADU calculates the total used fuel, which is also stored in the device memory. The total used fuel is the sum of the deltas between the current ecu.usedFuel and the previous ecu.usedFuel.
Something like this:
totalUsedFuel = previous totalUsedFuel + (current ecu.usedFuel - previous ecu.usedFuel)
That means that the ADU does not need a value that is zeroed out, but can calculate with an continously increasing number ?
The calculation is done with the raw value or with the value already converted to liters?
How does your ECU communicate the amount of used fuel?
I communicates fuel used in L X.XX (like you said) but it is not zeroed out at ecu restart.
So its fine - it will work correctly
However, you need to set the parameter “Max used fuel change” properly.
If your ecu.usedFuel is less than “Max used fuel change”, then this value will be added at ADU startup to the total used fuel (and subtracted from the remaining fuel).
So this will affect the VFT feature after the ECU used fuel is reset, until it reaches the “Max used fuel change”. You may need to adjust the “Max used fuel change” parameter to mitigate this scenario.
Thanks a lot. Got it to work! Nice 
Ok, need to investigate that “Max used fuel change” a bit more to understand it perfectly. What is the exact purpose of that feature?
Max used fuel change - Maximum acceptable difference between two consecutive readings
of fuel consumption information. If the change is greater than this parameter, it will be ignored. The parameter also enables the function to work correctly if the fuel consumption channel in the ECU is reset
If you want to learn more about the Virtual Fuel Tank, you can check out the How-to guide here: https://www.ecumaster.com/files/ADU/HowTo/How_to_Use_Virtual_Fuel_Tank_in_ADU.pdf
Thanks Michal, but I read the documentation multiple times before, but for me the information is not very clear.
My VFT works fine now. Even though I don’t understand fully the “Max used fuel change”.