I was just curious if the readings the computer take are from a flow rate
meter or some other method of determining mpg? When I use it on the Hwy, I
get a pretty accurate reading when compared to how much fuel vs miles on
the odometer. However, when I use it around town It will read say 15.2 mpg
and my fuel calculations will be 1 to 1.5 mpg higher.
Thanks in advance
Based on various engine parameters, the computer knows how much fuel it's
squirting (or should be) via the injectors. It takes that, combined with
the odometer information, and calculates an average. So, if you put in
higher-flow injectors, it throws the calculations off, because the computer
is assuming a flow of 'x' amount of fuel, not '1.2x'. The same is true if
you have clogged injectors.
If you're using the average (some years also have an instantaneous display),
that's an average over (I think) the last 30 miles, so it could take some
time to adjust to the lower economy of city driving.
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