Wideband AFR 0-4v Output Programming for 3rd Party ECUs and Data Loggers

Many customers looking to to use the data output require a formula to put into their 3rd party logger or ECU to interpret the output voltage from the gauge. The upper and lower set points of the Wideband Pro gauges are user adjustable and therefor no single formula can easily be applied to every application. Here’s an explanation of how to create the formula depending on your low and high bar graph display (BGD) settings.

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 ) / (4v – 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 4v the formula looks like this:

y = ((6/4) * v) + 10

or it can be simplified as:

y= 1.5*v+10

If we plug in 1.25v into that equation then we get: 11.875:1 AFR = (1.5*1.25) +10 which falls right along the plot chart.

If you were to adjust the BGD endpoints to say 11:1 and 15:1 then the formula would be modified to look as follows:

y = ((4/4)*v+11 simplified to y=1*v+11 or y=v+11