Quote:
Originally Posted by kamsmart
Dan, any updates on your experiments?
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Well I tried it this morning, but the engine was cold, so it was in the 50s.
One problem I do have is rounding error. Since I use the FCD to maintain my tank average, the only way I can measure fuel consumption is:
(Me - Ms)/(Ge - Gs)
Where:
Ms = FCD MileageStart
Me = FCD MileageEnd
Gs = GallonsConsumedStart
Ge = GallonsConsumedEnd
To solve for Ge and Gs I use the following:
Ge = Me/MPGe
Gs = Ms/MPGs
Where:
MPGs = FCD mpgStart
MPGe = FCD mpgEnd
Now enter rounding error. If MPG reads 53.5, it could actually be anywhere between 53.45 and 53.54 (both of which round to 53.5). Same with mileage. 474.3 could be anywhere between 474.25 and 474.34.
So if
Ms and
Me are both large numbers (as they are at the end of a tank) then the swing accounting for rounding over a 2 mile track can be huge. In this particular example I believe the swing comes out to anywhere between 39mpg and 81mpg based on a 53.5 mpg read.
So unfortunately, until I can find a sufficient track in the Houston area, I don't know If my measurements will be very helpful.
I am working on a new spreadsheet to give me the range that the values are in accounting for rounding, but I'll have to get some data first.
One thing that might help... does anyone know if the FCD does rounding or truncation? I assumed rounding, but it may truncate based on my trip -vs- FCD mi numbers.