Scanguage II Calibration: 'Adjustment Factor on Fillup'

[smartzuuk]

As per the manual:

"The screen will show how much fuel the ScanGauge has computed to have been used since the last time a FILLUP was done. Use the value displayed by the pump or on the receipt to adjust this value up or down (using the upper buttons) to match it as close as possible. The lower line shows the ?adjustment factor? in percent that the ScanGauge will use to compute fuel use. Press DONE after you have finished adjusting the indicated fuel to match the actual pumped fuel. Pressing DONE enters this correction factor into flash memory"


I'm thinking that the adjustment factor on the fillup is something I will ignore from here on...

When I first got the unit, I did a fill, and then told the Scanguage I had done a fill, but did not put in the real amount.

I then drove for a day, and did another fill - adjusting the fillup in Scanguage to match what I had actually used. The 'adjustment factor' was 19.4%

My next tank was 4.0 L/100 (7.7 litres / 192 kms), but Scanguage showed 4.7

If that 19.4% had actually shown zero, I'm thinking the fuel economy in Scanguage for this tank would have matched... ? Am I correct?

I have verified and adjusted the Scanguage speed against a GPS, and verified the distance travelled on a longer trip, and I am within 2/10 of 1%... (I wish you could enter more than just whole numbers for this adjustment - I could make it exact...)

Is this likely to be the only calibration required? It seems the fillup amount 'adjustment factor' introduces too many variables... did you use the same pump, facing the same way, filled to the exact same level... and add to that exaggerated differences on partial fills...

How have others done it? Any examples of how the fillup 'adjustment factor' has helped? Have you averaged out 10 fills FE at the same pump against the Scanguage FE for the same?