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Old 11-01-2011, 05:04 PM   #12 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
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A compromise between finding & installing a fuel flow based meter (instant feedback) vs. tank-to-tank MPG calculations (feedback may be too slow for those trying to evaluate mods) is to calibrate your fuel tank sending unit and effectively create a "trip gauge".

- With your tank nearly empty, connect a digital multimeter to the fuel tank sending unit (measuring resistance)

- Add a small measured quantity of fuel (say .25 gal)

- Note the change in the multimeter reading

- Repeat until tank is full (multimeter reading stops changing with added fuel)

Now you have a graph with decent resolution of fuel level vs. sending unit resistance, which you can use to figure out fuel consumption. (Assumes you park in the same spot as when you calibrated the sending unit... and the sending unit isn't sticky etc. etc.)
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Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
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