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Old 05-28-2009, 02:09 PM   #3
growling_boxer
Scooby Specialist
 
Member#: 165744
Join Date: Dec 2007
Chapter/Region: Tri-State
Location: Eastern PA
Vehicle:
2018 Crosstrek
2005/7 STi

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Quote:
Originally Posted by Bluefoton View Post
Why are the MPG readings useless? They are not related to fill-ups at all. You get the instantaneous. trip, and daily mpgs fairly accurately. The fill-ups are needed only to see the nr of miles left / gallons left in your tank.
the numbers change by a good bit if i fill up at a pump that shuts off well before the top of my tank, which seems to happen fairly easily with my STi for some reason. when I am actually able to fill all the way up, it changes the amount i fill by 2-3 gallons. just that difference starts throwing off the MPG numbers by about 10% for the same style of driving on the same route. After a track day or two, it gets extremely confused and my MPG ends off by 50% or more, and it takes a couple fillups to recalibrate. It seems to estimate everything without being related to the level reading. I assume it is using something like the TPS to estimate the MPG.

Quote:
Originally Posted by Bluefoton View Post
As far as the speedo goes, the Scangauge also calculates it based on your tire rotations per minute (and a default tire diameter) - there is nothing to make it accurate unless you calibrate it (which is why you have that option). Your only call is a GPS from which you can then set your Scangauge speedo, and see if it matches the dash speedo.
i did calibrate based upon distance as it explains in manual. at 0, it reads the real number rather than boosted number on the gauge for stock size tires. when I go up 2 tire widths without changing the sidewall ratio, the 2 setting works beautifully. now when I drive past a radar sign, my speed is dead nuts on what is read by the sign. I don't need no stinking GPS...thats what my compass is for
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