SG calibration off - MPG readout low

[BabyDiesel]

Top of the morning, eco-peeps!

Here's the situation at hand: The SG readout for the instantaneous MPG is low, and is affecting the AVG. I filled up last night, doing my usual protocol (cutting the pump of @ ~7 gals, waiting 15 seconds for foam to dissipate, then filling up till the pump cut off, and topping off by adding just enough gas to get the next "0" ending in the cash value. Weird, I know. OCD ) 10.897 gals @ 3.019/gal for 89 octane. $32.90 SG reported a tank average of 41.6 mpg, and the actual was 40.91... this is the farthest margin of error over the past 3 tanks.

However, I decided that I wanted to change it up to get more days and miles from a tank. So I went ahead and topped off the tank all the way to the top. The final amount of fuel was over 12 gals! This is the amount I entered in to the Fillup on the SG.

This morning, I averaged 36.1, according to the SG I nearly always get above 40, even if I am in a hurry. Could the intentional overfilling cause the AVG mpgs to be this low?

Thoughts?

[oldtamiyaphile]

IMO, once you get a calibration you're happy with, stop messing with it. Just go to fill up> OK. Don't change the value. You'll drive yourself mad otherwise.

Overfilling will cause the issue you describe. If you know the original calibration (in percent), you can go into fill up and change it back. Your next fill will be off by the amount you've already used.

If you find a new technique or mod changes calibration over a couple of tanks, then you may wish to recalibrate.

[gone-ot]

O C D = Oil Consumption Delirium

[2000mc]

highly inacurate = 0.2gallons on a fill over 10gal for you?

+/- .3gal on a 10gal fill is typical for me, so i'd be happy w/ 0.2gal. to try to be more accurate i started tracking the SG readings / trim setting in my fuel log, so that i can look back several tanks before trying to make an adjustment

[BabyDiesel]

Originally Posted by oldtamiyaphile

IMO, once you get a calibration you're happy with, stop messing with it. Just go to fill up> OK. Don't change the value. You'll drive yourself mad otherwise.

Overfilling will cause the issue you describe. If you know the original calibration (in percent), you can go into fill up and change it back. Your next fill will be off by the amount you've already used.

If you find a new technique or mod changes calibration over a couple of tanks, then you may wish to recalibrate.

Thank you a lot for the clarification I changed it back this afternoon and the figures reflected their normal amounts.

O C D = Oil Consumption Delirium

Made me LOL Tele man!

highly inacurate = 0.2gallons on a fill over 10gal for you?

+/- .3gal on a 10gal fill is typical for me, so i'd be happy w/ 0.2gal. to try to be more accurate i started tracking the SG readings / trim setting in my fuel log, so that i can look back several tanks before trying to make an adjustment

2000mc - Yes bud, it was when it has been less than 0.1 gals off for the past month in hindsight, that is only 2% off... a SG can't get much better I suppose!

Thank y'all for the quick feedback. Members like y'all make this site so great