Stack LAMBDA Guide D'installation page 5

BGD Range Setting Mode:
The Bar Graph Display (BGD) Range Setting Mode allows you to fine tune the resolution of this instrument for your specific application.
With upper and lower set point adjustability, you can set the BGD to utilize the exact range that the engine / vehicle operates within and
see exactly how rich or lean you are running in relation to your current set up and tune. Adjusting your BGD limits also adjusts the scaling
of the 0-5v data logger output supplied from the gauge. The selected low set point of the BGD Range becomes the 0v value of the data
logger output. The selected high set point of the BGD Range becomes the 5v value of the data logger output. Whenever you change these
points, the instrument adjusts the data logger output so that the 0-5v signal is always linear between your chosen set points.
To view your current BGD Range HI / Lean setting or LO / Rich setting:
• From Real-Time Mode, press MODE (-) to scroll until the display indicates "dSP", then press SELECT (+) to display your current
BGD Range set point.
• The SSD of your display will show "HI" in the display to indicate that you will be viewing the "above Stoichiometric" or
"Lean"upper range boundary.
• If you would like to view the LO / Rich setting, press MODE (-) when "HI" is shown on the SSD. The SSD should
now indicate "LO".
When the desired setting, "HI" or "LO", is displayed, confirm this selection by pressing SELECT (+). The upper or lower BGD range
value will then be displayed in the SSD of your gauge corresponding to your selection.
Note: When your selection is made and the numeric range value is shown, LEDs in the BGD will light to indicate which set point
you are viewing. If the LEDs to the left of center or Stoichiometric are lit, you are viewing the "LO" or Rich set point. If the LEDs
to the right of center or Stoichiometric are lit, you are viewing the "HI" or Lean set point.
If neither button is pressed for 3 seconds after the BGD Range "HI" Setting is displayed, the gauge will return to Real-Time Mode.
To Change your BGD Range setting:
When the current BGD Range "HI" or "LO" set point is displayed, press SELECT (+) to increase your chosen BGD Range setting,
and MODE (-) to decrease your BGD Range setting.
• After you have selected your new BGD Range set point, the gauge will flash your new set point 8 times on the display
and then the SSD will display "S C" for Save/Cancel.
To confirm your new BGD Range setting, press MODE (-). This will save your BGD Range set point changes
•
and return the gauge to Real-Time mode.
To cancel the changes and return to your previous set point, press SELECT (+). This will cancel the BGD Range set point changes
Data Logger Output Range:
The STACK Wideband Air / Fuel gauge has a signal output for supplying information to a Data Logger or engine management system. The sig-
nal provided is a linear 0-5v output. See the BGD Range Setting Mode for information about how to define the air/fuel mixture values for low (0v)
and high (5v) ranges of the output in order to scale this linear signal output for best operation with your Data Logger or engine management.
The formula to determine the AFR output from the voltage provided by the gauge is derived from y=mx+b (algebraic equation for a straight line),
where in our needs the following applies:
y = AFR
m = slope of the plotted line (BGD AFR High - BGD AFR Low ) / (5v - 0v)
x = output voltage from the gauge
b = offset or AFR value at 0v
Using the default values of 10:1 AFR for 0v and 16:1 AFR at 5v the formula looks like this:
y = ((6/5) * v) + 10
or can be simplified as:
y= 1.2*v+10
If we plug in 1.25v into that equation then we get: 11:5 AFR = (1.2*1.25) +10 which falls right along the plot chart. If you were to adjust the BGD end-
points to say 11:1 and 15:1 then the formula would be modified to look as follows:
y = ((4/5)*v) +11 simplified to y = 0.8*v + 11