Partial fillups with Scangauge
 

Has anybody figured out a way to partially fill a car with a scangauge with messing up the calibration. Because the SG assumes you filled up,it would be off if I entered only 5 gallons because that's all I put in. Also, wonder wonder why nobody has created an add less than a tank feature to the SG. Do other options like the MPGuino have it?

...I'm a noobie to the SGII, but I'd simply 'check' the gallons used that it (SGII) reports against the actual gallons-pumped, and if they "agree" (close enough), simply press "DONE" and "SAVE"...that'd restart the MPG cycle.

How would that work? Wouldn't the gallons pumped normally be less than the SG predicted if you stopped filling before the tank was full? Unless the SG was off. That would cause the SG to think it was getting better fuel mileage than it actually was.

...no, the SGII's FILLUP function is reporting how many gallons of gasoline it "calculated" as being used, you enter how much was "actually" used.

...it's part 2 of Step 4) Calibrating Your ScanGaugeII process:

Part 2 - Your Second (or subsequent) Fill Up:

1) When the tank is around 1/4 full, fill up your tank again. Be sure to let the pump shut off automatically.

2) Use the FILLUP function to tell ScanGaugeII you have filled the tank. From the Home screen, follow the sequence: MORE>FILLUP>

3) The next screen will show the amount of fuel your ScanGaugeII believes was used since the previous fill up. Use the upper left and right function buttons (A,C) to adjust the amount of fuel you actually put in the tank. <---this is where you're actually "calibrating" the SGII.

4) Push the DONE button.

5) After pressing DONE, the fuel COST screen will appear. Enter the cost per gallon/liter and press the SAVE button.

I think your misunderstanding my question or I'm misunderstanding your answer. I'm asking if anyone knows what to do if for some reason you stop filling the tank before the pump clicks off(For example if I have to use a 5 gallon can). Or if you just want to run less in the tank to reduce weight.

...I'm saying, just treat it as a "short fillup" and start over again, hence my previous statement: "...that'd restart the MPG cycle."

...if you make no changes (ie: don't press the A or C buttons), but continue thru the setup process, you're effectively "re-starting" the MPG cycle.

Wouldn't that mess up the SG's calibration because it uses the fillup figures to calibrate itself? If you adjust it to what you put in, the SG will think the car used less fuel than it predicted. If you just agree with what it predicted, then the next fillup will be off.

...as I understand it, there are two options:

1) restart (what I've been discussing), or...

2) postpone the whole situation and simply add the 5 gallons to the "next" pump fillup number, and definitely do a FILLUP calibration.

...I do a FILLUP calibration with "each" tank fillup, just to see if there are any changes going on, and if so, by how much and in which direction.

Sounds like the second option would work as long as you right down the amount you put in for the partial fillup. Although I wonder if the SG would notice if in some case the amount you put between the two fillups exceeded the tank capacity you inputted.

...good question. As I mentioned at the start, I'm a noobie to SGII who's only good for regurgatating the already written directions (at least I've read them).

...maybe somebody else here knows of "tricks" that might help?