Little silly thing I noticed while going through ODBII readings from the MAF sensor. The readings it is supposed to give out is in grams of air per second, but I was skeptic at how accurate it was. Then tried to do some simple math.

At cruising speed around 65mph it was consistently showing ~48g/s. Soooooo….. if the stoich is 1:14.6, that means it was using 48/14.6=3.29 grams of fuel per second, which translates to 3.12 gallons per hour. And 65mph / 3.12 = ~20.8mpg! Dead on with what I get when measuring it at the pump with pencil and paper! Conclusion: MAF readings are pretty damn accurate.

At warm idle it shows 4g/s so that translates to roughly 1/4 gallon per hour of warm idle! Just an interesting figure to know

 

Thats very interesting to know! I bet everyone has heard of those stories where people, usually old laides, get stuck in a snow storm and have to keep thier engine running to stay warm. I've always wondered how I could calculate how much time I would have. I've got a 1st Gen so I don't think I have ODBII readings though.

Erich

 

yeah, but here's the cool thing. i have a 1st gen too, so i don't have obdii, but we still have the maf and the o2 sensor and those things. a real cheap way to record those output is to hook up the output of the sensors to the input on a minidisc (or any other music recorder). the output of the sensor can be mapped to music, which can then be played back on your computer and you can do some math with the waveform to back out the actual values. i'm actually in the middle of setting up something that i can plug into the audio input of my laptop and get real time info just like the people with obdii get do.

 

And if you play it backwards you can hear Jerry Garcia playing "Friend of the Devil".