Fuel Used Error

MadWilly · September 28, 2006

I have a 2005 Duramex Siera. When I fill up at the pump, I constantly have the wrong fuel used in the driver info center on the console. This leads, of course, to the wrong average fuel economy. Is there a known bug in the computer? Or is there a way to align this value?

I was told by a service writter that the comnputer just uses the tank float to determine the quantity of fuel used.

95Sierra2500 · September 28, 2006

I don't know how it determines it, but I know that most of them are off by .2 to .5 gallons, perhaps more. Very rarely is there one that is dead-nuts. Besides, it's not really supposed to be super accurate, just close enough to warn you when you're gonna run out of fuel. Might happen sooner, might happen later, but it's just for those who don't watch their gas gauge.

GM-Tech · September 28, 2006

Never had a problem with this so I have little experience with how it works. I see from "Description and Operation" in our service information that this can display fuel used for each trip odometer (A and B). I don't know how it would calculate fuel used if the trip odometers are not reset and one of them turned on.

I could be wrong, but from the way I'm reading it, it does not appear to use the regular odometer for this. If it did, this fuel used number would just continue to grow over the life of the vehicle and you'd have a number that's pretty meaningless.

So, what are you calculating this on? Reset Trip A to zero and turn it on at your next fill up. Next time you fill up, see how many miles accumulated on trip A, divide that by the amount of gas required at that fill up and see if gas mileage is about what it should be. And, check "Fuel Used" in Trip A against what you just pumped into the tank.

03blackburb · September 28, 2006

I check my mileage at every fillup and compare the DIC numbers to the actual amount pumped/paid. In over 3 years it has never been off by any more than maybe a .1 or .2 of a gallon overall. Not sure what it uses to do the calculations but in this 03 suburban it is very close.

asilverblazer · September 28, 2006

My Caddy calculates fuel used by injector pulse width. As well as fuel economy numbers. I think the float method is a highly inaccurate way to gain those readings, so I doubt that is how its done.