Scangauge and Partial Fills
 

Now admittedly I may not know everything about my scangauge, but I have noticed one fatal flaw in my own unit.

They do not like partial fills. Now I know I cannot do calculations on mpg based on partial fills, but my scangauge goes haywire when I hit the fill up button.

For example, the other day I added 3 gallons of gas to my xD, when I went to hit the fill up button it read 9.78 gallons. Now if you make the manual adjustment it throws off your reading incredibly taking over three full tanks to balance back out.

Am I missing something? Is there a way to keep the scangauge accurate with partial fill ups?

Thanks ..

...ah, but you CAN do calculations on partial fillups, simply ADD the partial MILES and GALLONS to the NEXT tank values...both sets of numbers are then 'averaged' together when you divide the added-MILES by the added-GALLONS.

Thank you for that, and yes you are correct, however I am talking about what the scangauge reads... When I do an entire fillup the scangauge registers the proper gallons of gas used to usualy one tenth. However if I have to do a partial fill due to economics lets say and I add 5 gallons, the scangauge reads it as a 9 or 10 gallon fillup and if you adjust it to reflect the proper amount of fuel the readout settings go hay wire.

I know this because there is no way in hell that my xD was averaging 97 miles per gallon on my commute home ... lol Would have been nice, but not true.

I am wondering how I reset my scanguage to defaults since it seems to be going haywire lately.

Unlike you I use my scanguage in many different vehicles and could care less about the fill up option unfortunately I have used it on "clean" tanks on one car or another and now it bounces all over creation and is getting less accurate.

I am wondering how I do that since it was moderately accurate when I started but now after being on the buick roughly 3 months straight its getting less accurate, as it gets colder my Scanguage reads higher FE while my real FE keeps going down, strange.

Anyway to use the fillup option you must add up your partial fills and MPG until you ACTUALLY fill the tank or it simply doesn't work. In other words like me you should get the thing reset put in whatever offset you figure you need and be done with it since partial fills cannot be used with the scanguage.

Cheers
Ryan

Thanks, now isn't that a bit strange?

Obviously when filling up it was accurate to a tenth, which was great. I wonder why it cannot accurately determine that 5 gallons was put in instead of 11? Is there anyway to provide them with feedback to help them develop a fix for this?

Ok so if you go and just put in 5 gallons, don't set the fill up at all on your ScanGauge at all. Instead write down the exact amount you added and wait untill you to fill the tank. Then add what you wrote down to what you filled up with and it should match what the ScanGauge says. The only thing that will be off is your miles to empty as you may be going over the capacity of your tank.

Hope that helps.

You do not want to change the offset when you do a partial fill. That's your problem. What I have is an average offset collected from several tanks. Then I leave it alone. It's within 1% of true. Whenever I fill up I record the SG gallons and my real pump gallons and add those to my spreadsheet to further pinpoint the accuracy. I don't ever touch the offset any more.

The adjustment is for a complete fill.
The SG tells you how much gas it thinks you put in to fill up based on the OBDII data it collected since the last fill up. It has no way of knowing how much gas you really put in.

You didn't fill up, so you shouldn't change anything. Just press fill up to reset the counter, and do nothing else. That way, the next time if you DO fill, you can calibrate it.