Scanguage II Calibration: 'Adjustment Factor on Fillup'

[smartzuuk]

Originally Posted by LxMike

i already filled and waiting to refill to check the accuracy too. sg has been showing my trips to work arounf 36-38 mpg but when i checked mileage was only 32.7. my wqay to compute mileage was that when low fuel light came on i put $20 in and next time light camer on i ised the number of gallons and miles drive3d to figure mileage. e-mailed ron at linear logics and he told me that i needed to do the corect fill and refill for best accuracy.

There is a bizarre logic in there... it makes sense if
a) the price per gallon is the same, and
b) you could know for certain the 'low fuel' light came on with EXACTLY the same volume of fuel remaining in the tank, and that you filled IMMEDIATELY upon seeing it light up.

Being that that is not realistic at all, what you really need to be doing is

a) fill to shut-off at a specific pump - and note your odometer reading...
b) then drive until you have used about 3/4 of a tank
c) refill to shutoff, at the SAME pump, and note your odometer reading

At this point you can determine the distance travelled, and since you now have a fuel volume to put against this, you can work out your mpg.

And you should be reasonably close to reality if you filled to shut-off at the same pump and filled at least 3/4 of a tank...

[LxMike]

Originally Posted by smartzuuk

There is a bizarre logic in there... it makes sense if
a) the price per gallon is the same, and
b) you could know for certain the 'low fuel' light came on with EXACTLY the same volume of fuel remaining in the tank, and that you filled IMMEDIATELY upon seeing it light up.

Being that that is not realistic at all, what you really need to be doing is

a) fill to shut-off at a specific pump - and note your odometer reading...
b) then drive until you have used about 3/4 of a tank
c) refill to shutoff, at the SAME pump, and note your odometer reading

At this point you can determine the distance travelled, and since you now have a fuel volume to put against this, you can work out your mpg.

And you should be reasonably close to reality if you filled to shut-off at the same pump and filled at least 3/4 of a tank...

Thats what i'm doing now but going out of town this weekend and will need gas on the trip home. i've only used 1/4 tank, so it's kinda early to do a refill. whixch mean when i do refill won't be at some station/pump. i could refill right before my trip but wouldn't take more than 3-4 gallons. might just do that for a short accuracy check and when back from trip (300 miles) check again.

[smartzuuk]

Originally Posted by LxMike

i could refill right before my trip but wouldn't take more than 3-4 gallons. might just do that for a short accuracy check and when back from trip (300 miles) check again.

That would be a good idea. You also should begin tracking your FE over a loger period of time as well, so you know what you are averaging overall.

If you do your fills as you suggest you might, you should also be able to get a quick reference against the Scanguage. Just ignore the fillup 'adjustment factor'... simply hit 'done' when you do a fillup so it starts tracking a new tank (or partial tank).