On 26 Sep 97 at 13:22, Andrew Warren wrote:

> Steve and Mike Smith (no relation, I presume) wrote:

Not within recent history.

>
> > 1. Consider a car with a fuel computer fitted and use the
> > information supplied.
> >
> > 2. As above but disconnect the fuel computer thus giving a raw
> > transducer output and reinvent the wheel.
>
> and
>
> > Steve's solution seems best for cars - especially when you
> > consider that every car made in the last 10 years would have the
> > computer/transducer already, just to meet exhaust emission
> > standards. Only the up-market models give a mpg / l/100km readout
> > though, so intercepting the blips the transducer produces and
> > converting to liters would be necessary.
>
> Guys:
>
> I don't think that cars with digital "miles per gallon" displays
> have flow meters in their fuel rails.
>
> I mean, think about it... If YOU were designing a fuel-consumption
> display for a fuel-injected car, would you get the information by
> installing two expensive flow-meters, measuring flow to the
> injectors and subtracting the flow back FROM the injectors, or would
> you go for the software-only method of simply accumulating the
> widths of the injector pulses and multiplying that by the known flow
> rate of each injector?
>
> I know which method _I_ would use...
>

I *know*  I'm arguing with an expert here, but consider some
drawbacks...
- dirty/ partially blocked injectors
- offspec signal applied to injector/s (battery/alternator issue)
- not all emission-controlled cars are injected - some are
conventional carburettors.

For a mass-produced item like a car, is a flow-meter really
expensive? (lets ignore rip-off spare parts prices, I'm thinking
cost)

MikeS
<mikesmith_ozNOSP*M.relaymail.net>
(remove the you know what before replying)