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Re: Mixture Gauge.

>Mark Gibson <Mark@domain.elided> wrote:
>Subject: Mixture guage (long)

>the computer "too lean" or "too rich", but it can't say "just right".  So   
>you get 0.1 V at "lean" OR 0.9 V at "rich" (or is it vice versa?), but   
>never, say, 0.45 V ("just right").

Output depends on type of sensor. There are (at least) two different
technologies used.

[Very good explanation snipped]

>P.S. I've always wondered how those mixture meters could possibly work,   
>given the response of an O2 sensor.  Guess they don't!

They may if there is an integrator circuit before the display.
This would work like if you used an analog pointer instrument
and immersed it in heavy oil. The fluctuations would disappear,
and you would get an average reading.

OTOH the rhytmic up/down flickering of the LEDs will tell you
that the ECU is operating in closed loop mode, which in itself
is reassuring.  If it detects some error and goes to "limp home"
mode, the flickering will stop.

If used on a carburetted engine, the gimmick could give you a
verification that the carb/engine is working the same way it did
after your last proper dyno tuneup. The clue will be to look for 
changing behaviour though, and not any hard figures.

Einar Sjaavik

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