John <welcomehowcome@hotmail.com> wrote:
Quote:
Hello All,
I'm pretty new to electronics and would like to take this chance to learn
more about electronics and at the same time create a useful gadget.
I would like to create an A/F (air/fuel display). Here are some of the
constraints, notes, and parts that will be used for this project.
-- air/fuel mixture will be fed from the O2 (oxygen sensor) located at the
header (it's for a 92 civic dx).
-- O2 sensor provides 0-1V
-- would like to use an LCD display of some type with 3 digits
-- would like to display the actual voltage provided by the O2 sensor in
millivolts up to three decimal places
e.g. O2 sensor reads 0.15V, I would like my A/F meter to display a
reading of 150
Later on would like to add three leds, one red, one green, one yellow...
red=volts<0.2V, green=0.8>volts>0.2, yellow=volts>0.8V... this would be a
quick glance indicator of what's the current status of the A/F mixture
without having to read the actual display.
I'm looking for any suggestions as to what components to use and how to
build this project. Also, any reading that might help me learn more about
electronics while building this project would be helpful.
|
Here's a better question... Whats the point? A standard narrow band
oxygen sensor is next to worthless for giving you mixture readings. They
have part/part variation. They vary with age and temperature (which is
constantly fluctuating). They are highly non-linear, and they exhibit
hysteresis. In otherwords, they read "lean", "rich", and maybe if you
are lucky stoichiametric. But under normal running conditions the ECU
will keep the AFR bouncing between rich and lean. The only exceptions
to this are when the car's cold (at which point the sensor isn't working)
or you are at wide open throttle, in which case presumably you are running
rich but you can't know how rich. Anyone who tells you differently is
trying to blow smoke up your backside. As for your "device", why not just
use a cheap digital multimeter? That should do exactly what you want, and
it's probably cheaper, more versatile and better packaged.
dan
Re: Air/Fuel Mixture Meter
Linear Mode
