Originally Posted by Right Lane Cruiser
Do you know if there is a way to tweak the percentages at a time other than fill? I don't really want to "start over" on the tank to get the settings tuned in...
Yeah, I was thinking of you when I posted.
For you it's easy... you simply unadjust the fuel. Do this by restoring defaults (then go back and set engine size and tank size and fuel type). That should remove all calibration and restore you to defaults. Taking off the +16% fuel calibration will give you a +16% fuel differential.. but if your interested in the math behind it for calibration....
OK... if your really interested, get your math hat on... it gets thick.
Speed first... that one is easy.
I've talked to the SG guy and he said that speed calibration and distance calibration are the same. The clock is gonna be pretty acurate, so +1% speed == +1% distance. So, you mentioned that you have 34.3 vs 34.1. So 1 - (34.3/34.1) = -0.58 %. So you probably don't want to change speed since since adding or subtracting 1 from .5 still leaves you off by about the same amount.
Now for the fuel calibration.
The way this calibration works is by adding or removing tenths from your gallons consumed. So if SG read 5.0 gallons consumed and you hit the left arrow on the fill up, you just adjusted it to 4.9, which was a 2% reduction (-2%).
Originally Posted by PaleMelanesian
Don't know about adjusting the gallons mid-tank. I wish you could. I filled up yesterday, and adjusted the WRONG WAY. I redid it after 20 miles by doing a new fillup. I'll just have to track the combined in Excel separately.
If you want to move this number mid tank, just pretend to fill up. The more gas into the tank you are, the smaller the swing a tenth is. If you try it 2.0 gallons in, then each tenth represents a 5.0% adjustment. If you keep the tank (never hit the fillup button) for 50.0 gallons, then each tenth moves it 0.2%.
So if your at +16% on fuel and you want your MPG to be adjusted 16% up, here's how it works. If x = unadjusted SG mile reading and y = unadjusted fuel reading, what you have reported now (since you haven't adjusted speed) is:
x * (1+0.0) / y * (1+0.16) =
x/y * 1/1.16 =
x/y * 86.20% ... So your adjusting the measured MPG down by 13.79%... so if you want it 16% up from the current reading... here are the calculations...
0.8620 * (1+0.16) = .8620 * 1.16 = .99 (actually equals 1)...
0.8620 = 1/1.16
0.8620 * (1+0.16) = 1/1.16 * 1.16 = 1.
The simple formula is this... SG adjusts your MPG based speed adjust (S) and fuel adjustment (F) in the following manner.
adjustedMPG = unadjustedMPG * (1+S)/(1+F). Remember F or S can be negative.
OK... Dan's getting back in his rocker