idea..

Paul Raley raleyp at UDel.Edu
Tue Oct 7 03:09:50 GMT 1997



> someone mentioned trying to locate fuel flow meter to use for a mileage
> calculator.  Why not have the ecu record the combined pulse width over a
> period of distance, based on the assumption that fuel pressure remains
> fairly constant, a certain distance traveled divided by the time the
> injectors are open == MPG. All is needed is a pulse input from oneor more
> of the wheels,  each pulse = a certain distance ,and the frequency is the
> speed.

why could you assume the fuel pressure remains the same?  on my nissan, not
only does the fuel pressure regulator (which not everyone has) alters the
pressure, but the ECU controls the voltage of the pump, thereby varying
pressure from 20psi to 60psi or more.   Don't other modern ECU's control the
fuel pump voltage?

If you have a digital dash as on the nissan, the speed sensor could be used.
This transmits two pulses for every revolution (optical).  The analog dash
uses the same setup except that its magnetic and located in the dash itself.
There are a number of Z's in the junkyard with these sensors located next to
the battery under the speed control device.

Paul R.





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