Maybe not digital, but what about the analog MPG meters that BMW's have had
just below the speedometer for as long as can remember.  I'm pretty sure
these existed before FI replaced carburation on BMW's, maybe not.  Anyway,
these meters respond very quickly to driving conditions.  Any idea if these
used a flow gauge?


Martin R. Green
elimar@bigfoot.com

----------
From:   Andrew Warren[SMTP:fastfwd@IX.NETCOM.COM]
Sent:   Saturday, September 27, 1997 6:53 AM
To:     PICLIST@mitvma.mit.edu
Subject:        Re: ?: fluid measurement

<SNIP>

> - not all emission-controlled cars are injected - some are
> conventional carburettors.

    True... And if you can find a carbed car with a digital
    fuel-consumption display, I'll buy a beer at the Embedded
    Systems Conference and MAIL it to you.

> 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)

      <SNIP>

    I didn't mean to imply that injector-pulse measurement was the
    ONLY way (or even necessarily the best way); I was just saying
    that I don't believe that EXISTING fuel-consumption displays use
    anything more complicated than that pulse-measurement... It
    doesn't seem reasonable to me that an auto manufacturer would
    burden its cars with the cost of ANY extra hardware just to
    provide a function as minor as a fuel-consumption display.

    The fact that fuel-consumption displays seemed to appear right
    around the same time that microprocessor-controlled fuel
    injection became commonly available, AND the fact that I've
    never seen a fuel-flow meter on an automobile engine, AND the
    fact that I know of no carbureted cars that provide a digital
    fuel-consumption display, would seem to bear out my hypothesis
    that the fuel-consumption "measurement" is handled indirectly by
    a software-only process that just looks at injector
    pulse-widths.

    Just my opinion, of course... I could be wrong.

    -Andy

=== Meet other PICLIST members at the Embedded Systems Conference:
=== 6:30 pm on Wednesday, 1 October, at Bytecraft Limited's booth.
===
=== For more information on the Embedded Systems Conference,
=== see: http://www.embedsyscon.com/

=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering - Vista, California
=== http://www.geocities.com/SiliconValley/2499