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Discussion Starter · #1 ·
I wanted to know how the instantaneous gas mileage feature on the dashboard is made? Is it a calculation made by a computer based on throttle position, RPM, load, injector duration, etc. or if there is a fuel flow meter or some other process?
 

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lou-in-usa said:
I wanted to know how the instantaneous gas mileage feature on the dashboard is made? Is it a calculation made by a computer based on throttle position, RPM, load, injector duration, etc. or if there is a fuel flow meter or some other process?
I would guess that there is a flow-meter, because it is pretty sensitive - possibly it knows how much gas is being sent thru the injectors based upon the computer, and it also knows the speed, and it does the division - however, my Average Fuel Economy calculation is always high, so IMHO, it is not that accurate on the '10s. Guess it got more accurate on later models.
 

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If the instantaneous mileage calculations are done as in previous years, it is done by the length of time the fuel injectors has are open. Sum up the time the injectors are open over a time period, multiply by a flow factor, and divide that into the distance covered during that time. Since you have several factors involved, the calculated value can be and is probably off by some amount.
 

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Discussion Starter · #4 ·
I would imagine the easiest way to calculate it would be the vehicle speed divided by the fuel flow calculation made by injector duration and frequency. That is how inkjet printers calculate ink usage. That would seem to be a simple and very accurate calculation.
Thanks.
If anyone knows if that is in fact how it is done, please post.
 
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