Does Scangauge Accuracy ever level off?

[bbgobie]

I've had several tanks now with my Scangauge. At each fill up its off by quite a wide margin. I'm kind of confused, because I thought with each fill up it would become more accurate. But instead sometimes I'm moving up to like + 5%, than the next fill back down to +2%. I've never had a tank within 1/2%.

So for you guys, does it level off? To where i'm off by like .1-.3% I can just leave it, or am I gonna have to adjust it 2-3% with each fill up!??

[Bill in Houston]

To me, when you try to calibrate a Scangauge with fill data, you can make yourself crazy if you adjust every time. I'd get it close, and then leave it. Over several more fills you might identify a certain bias, and correct for that. But messing with the calibration every tank doesn't make sense to me.

[Mentalic]

Originally Posted by Bill in Houston

To me, when you try to calibrate a Scangauge with fill data, you can make yourself crazy if you adjust every time. I'd get it close, and then leave it. Over several more fills you might identify a certain bias, and correct for that. But messing with the calibration every tank doesn't make sense to me.

Makes sense to me as well. Adjusting often takes you down the path of over control. You need to collect enough fill up data points to get a good average.

Try to use the same station and pump every time, even the same time of day due to temp changes. All pumps are accurate enough but due to the angles of the parking lots and different click off pressure theres going to variability in your results if you don't use the same pumps.

[JanGeo]

Yeah leave if for several fillups - the engine braking fuel cut off throws it off a lot and the pump can as well has how much you fill it can result in some error - prior fillup was 0.3 gallons off last fillup was right on but I pumped more in than usual - I know this because instead of 80-90 miles to get the needle down to the full mark I went 107 miles so only adjust on over 10 gallons and on a good two full tanks in a row where the gas is at the cap. Otherwise it throws off all the mileage readings that it gives.

[bbgobie]

Thanks guys. I just thought it would be a little more accurate.

[Bill in Houston]

Okay, try this thought on for size. If the scangauge were perfectly calibrated, you would still see disagreement between the SG and the fill method, right? So, to me, once you get the SG calibrated, it is correct. Any difference you observe in the calibration after that is a result of the inability to consistently fill the tank. See what I mean?

[usedgeo]

I think that if it is close you should watch it for several fills. However if it is off quite a ways and you don't have a history I would put in 1/2 of the indicated correction. Or what seemed like a reasonable fraction.