ScanGuage II problems

[leetramp]

Hi all,

I've had some problems with the MPG readings on my ScanGuage II on a 1999 Saturn SW. When I first installed the SG on my "new" (new to me, 94k) wagon, I found the MPG readings way too low (in the 20's, while I knew from fill ups I was getting high 30's). In a thousand or so miles, I played with it a bit, trying different things. Then suddenly it started working correctly. Unfortunately, I had been toying with it without really keeping track of what I did each time, so I don't know what I did last. But either way, I don't think there's really anything in the SG to set, other than the tank size which won't effect MPG.

So, everything was fine for a 6,000 miles or so, then I had to take off the SG, and suddenly I'm back to the problem of low MPG readings (again, I have checked this against actual miles and fill ups).

Any thoughts on what might be wrong?

Thanks.