BIG_MODS

iTrader: (9)

I was wondering if anyones every built a MPG meter using the pulsewidth and vehicle speed from the ECM. I know that Lincoln's and some other cars had them from the factory and I don't know why some of the brains from this site couldn't rig one up. I know people have built shift lights using the ECM, so I don't see why they couln't make a MPG meter/gauge.

I can figure out how to relate pulse width and vehicle speed to MPG, but I don't have the first clue how to take this info from the ECM and display it on a digital gauge. How could this be done?

JPrevost

Forget about trying to figure out pulse width to fuel flow. That's more complicated than just measuring the flow of gas going to the injectors and then going back into the tank. That's as accurate as you'll get unless you've got an oscilliscope and a injector flow bench.
You could just figure out how much gas is in your tank and have a lag filter or a merc level switch to only activate input when the car is level or near 0-g's. It wouldn't be easy. Still need to figure out exactly how much gas is in the tank during your sending units output and plot the results. Then use that in the circuit or do source code and have it as an extra input into the ecm.
When you do it let me know.

pontiac

84' Corvette with digital dash have MPG meter or liters/100km meter. i don't know if newer vehicles like f-bodys or corvettes with digital dash had such a feature. but my bet is, information came from ECU



-P

pontiac

this is just my 3 cents (euro):
the amount of used fuel is direct function of pulse width. fuel pressure is constant, also injector flow and unused fuel return to fuel tank.

should be easy to have such a meter.


-P