How is fuel use calculated?

[sparky65]

Does any one know how the computer calculates fuel use. You know the thing in the upper console that tells use total fuel use. The reason i ask is because my fuel gauge is messed up bellow a 1/4 of a tank and I want to have a second check incase it goes bad completly. I am setting the trip odometer but thought the computer may use diferent sensors then the fuel gauge.

[1999montana]

Originally Posted by sparky65

....Does any one know how the computer calculates fuel use. I am setting the trip odometer but thought the computer may use diferent sensors then the fuel gauge....

I think the engine computer counts the number and duration of pulses for each injector to determine how much fuel has been used. The information is then calculated in US gallons or liters against the distance traveled (since start-up or reset) to detemine the fuel economy shown in the DIS display.

I don't think the DIS looks at the fuel gauge as the output from it is analog versus digital.

The display is an approximation however. I often find that it is out by a gallon or so when I refill the tank after a long trip, but this discrepancy could also be the result of the 'adjusted volume' (at 15 degrees Celcius) at the gas station pump too.

Someone else may have a different opinion however.

[sparky65]

I tested it and noticed teh same thing was off by 1.5 gal. The computer read 21 gal and i pumped 22.5 gal. Seems pretty close considering the amount of variables. Seems like a pretty reliable backup just remember to reset it and record how much you put in.