Scangauage II constantly reading higher MPG?

[Xhifer]

Hi, I have been using the Scangauge II on my 2000 Chevrolet Camaro Z28.

I set everything up correctly. (ie. 5.7 Liter engine / 16 Gallon gas tank)

Last fill up I did about 200 Miles and filled up. The scangauge says I'm getting 28 MPG with about 80% freeway. but when I filled up at the same pump it was 23 MPG...

I did a 320 Mile trip today and it showed that I was getting an average of 31MPG but when I filled up at the same exact pump it calculated to 26.5MPG.

I am not hypermiling or anything, I'm just driving normal and a few WOTs

Is Scangauge always a little off? How do I calibrate it to be spot on or at least near.

Thanks

[NeilBlanchard]

When you fill it up, are you calibrating it, by putting in the correct fill up quantity? Do you have the Speed calibration adjusted?

[Xhifer]

How do you calibrate the speed?

[MetroMPG]

Did you get a manual with your ScanGauge?

First make sure your speedo/odo is reading correctly (GPS comparison, or drive a pre-measured route). The manual explains how to calibrate the ScanGauge speed to real world (you enter a % offset if you find an error in your OEM speedo/odo).

There's also a fill-up procedure that will calculate a fuel volume % offset, or you can calculate the difference in fuel consumed and enter the offset % manually. It's fairly normal for the ScanGauge to be off by a few percent at least.

PS - if you don't have your manual, you can download a PDF from the company's site.