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Originally Posted by McTimson
It uses pulse width.
When you first set it up, you can use values close to what you expect. The beauty of it is, it's very easy to calibrate the values for what you're actually getting. Just pump gas at the same station, same pump, 2 times in a row, and you can adjust the value in the mpguino to reflect the amount you actually used.
My mpguino's reported gas usage is usually off by maybe +/- .2 gallons, for about a 10 gallon fillup.
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OK this is where I have a problem trusting it. I'm running in open loop all the time.
Pulse width base on calibration from actual data received from the filling at the pump station. Your relying on the variable filling at the pump.
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Just pump gas at the same station, same pump, 2 times in a row, and you can adjust the value in the mpguino to reflect the amount you actually used
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Back to square one.
I use the same filling station and the same stall every time.
If you just rely on pulse width, your actual volume won't be right. Injectors don't flow them same through out their duty cycle. their not linear.
Voltage injector dead times play a huge part in this at low pulse width 3.0 m/s or less.
To me all this gadget is doing is taking the pulse width after you calibrate it and tracking usage based on pulse width. Not the weight of the fuel or volume.
If you fill at the pump, you have the same variable, the variable of getting the same fill every time.
If your voltage changes at the fuel pump it won't be accurate.
If the density of the fuel changes it won't be accurate.
Pulse width is just pulse width. It open and closes at a given time
per-engine cycle. Its not a flow meter.
Now I'm not saying my last fuel log was right. I need to do a long mile test run. I'm not to sure what that should be after reading on here that the New York test (Chang's 118mpg CRX) thought a 100 miles was good enough? I guess not?
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The rally, organized by the Adirondack Motor Enthusiasts Club (AMEC), took place August 23 over 104 miles of scenic, lightly travelled, winding roads through the southern Adirondack mountains (with admittedly very MPG-friendly speed limits of 45 to 55 mph).
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Would you guys agree that the
coefficient of volume expansion of gasoline is 950 x 10-6????????