PLX as lambda in scanner

[sikhabib]

what would be the fomula to setup a plx sm-afr wideband to show units of lambda in the scanner (i dont think it matters but im using e10)

wideband specs......
Accuracy: < 0.1AFR (Gasoline) Wideband, < 0.2AFR (Gasoline) Narrowband
Measurement Range: 10-20AFR, 0.68 lambda - 1.36 lambda
Analog Outputs: Wideband Linear 0-5V, Narrowband 0-1V (Driving Current 20mA)
Operating Voltage: 8V-18V
Power Consumption: 30 Watts (Max), 18 Watts (Typical)
Power Supply Technology: High Efficiency Switching
Operating Temperature: 0 - 85 Deg C

thanks

[DSteck]

(Voltage * 0.136) + 0.68

or

(Voltage / 7.353) + 0.68

[sikhabib]

thanks for that

how did you come up with those numbers BTW

[DSteck]

Basic math... or use Excel.

0V = 0.68 lambda
5V = 1.36 lambda

The transfer function is ax + b, where b is your zero intercept and a is the slope of the transfer.

b = lambda at 0V = 0.68
a = (difference in lambda)/(difference in voltage) = (1.36 - 0.68)/(5 - 0) = .136

To get it in the form HP Tuners uses, use the inverse of a, which is 7.353 (1/a).

[sikhabib]

thanks mate that explains it perfectly