milage indicator

[Brian Warburton]

If you do want to do it all from the injector pulsewidths you'll need to
factor in the injector opening and closing time and because of that you'll
also need the battery voltage as that has a direct effect of injector
opening time. A pulse width of 4mS measured at the injector will NOT flow
twice the amount of fuel as a 2mS pulse. Also, a 4mS pulse with VBAT =
14.4v flows a lot more fuel than a 4mS pulse with VBAT = 12v because the
injector opens a lot faster with the higher voltage.

To give you an idea of the achievable accuracy, I originally wrote the Ford
EEC-iv tripminder code for the 2.0L DOHC back in 1987 and the required
accuracy then was < 5%. We achieved better than that, but not a lot better
!

Regards, Brian
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