ScanGauge II calibration question

[NeilBlanchard]

Hello,

I noticed today that the Trip odometer on the ScanGauge II reads a different distance than the car's odometer -- it was about 0.5 miles more in about 34 miles. Is this because of the calibration of the fuel, or what else might it be? It is hard to think how the distance could be calibrated by the fuel adjustments? What might be causing this?

It (the SG II) is actually closer to accurate, as far as I can tell. My current tires are slightly larger diameter than my winter tires, and my previous summer tires, so I have calibrated the odometer against the mile markers on limited access highways; over about 25-35 mile distances. The odometer registers about 5.5% less than the mile markers indicate.

Now I need to do this with the SG II at the same time to see what is going on. Does anyone have any insight on this?

[bossfrog]

The fuel adjustment should not affect speed and distance on the ScanGauge II. To calibrate for tire sizes use menu MORE>SETUP>SPEED. it is on page 16 of the ScanGauge manual.

[NeilBlanchard]

Okay, I started to calibrate the Speed setting on my SG2 today, and I got some interesting results.

I drove a measured route (the one for the upcoming mileage contest sponsored by Acton Toyota and CleanMPG.com May 15th), that is 24.3 miles long as measured by Hobbit's GPS:

MPG rally 2011

I already had the Speed calibrated by '3' (my unit doesn't display a % symbol), and I drove the route, and got 22.5 miles on the stock odometer, and 22.9 miles on the Current Trip measurement. Please notice that 22.5 + 3% = 23.1, which is not all that close to what it showed.

So, I tried to figure out what factor would increase 22.5 up to 24.3, and I came up with 20 -- but it was obvious that was way too high by the time I got to the 5.8 mile turn onto Gay Road, so I did some more estimation, changed the factor to 10, and reset everything and returned to the beginning of the route, and it seemed a bit too high still, so went down to 9.

I drove the route a second time, and the stock odometer said 22.5 miles (same as before) and the SG2 Current Trip was 24.0 miles -- nearly there!

So, I increased the Speed calibration factor back to 10, and drove the course a third time -- and very strangely, the SG2 Current Trip now said 23.7! Wassup 'wid dat?!

Doing the math to correct the 22.5 miles on the odometer up to 24.3 is almost precisely 8%. Which is great, but I am even more puzzled about the SG2...

I ran out of time, but I am very curious to drive the course with the Speed factor set to 8 -- maybe somehow the time vs distance = speed calculation gets better when the factor is right on? Hmmm...

[gone-ot]

...LinearLogic really needs to change the MILE adjustment to REVS-per-MILE (rpM), so a simple integer number can be entered. So we could simply start with the number provided by the tire manufacturer, then adjust up/down by interger numbers.