[dannichols1474]

I decided I had better check out the Point 2 calibration value more closely.

I went back out to the garage with my notebook running the TunerStudio app and connected the notebook to the ECU and turned key ON, engine OFF. I unlocked the calibration tables and opened the AFR calibration table.

I decreased the Point 2 calibration value from 20.100 to 20.050, wrote the value to the controller, then cycled the key OFF to ON, engine OFF and read the AFR gauge: 13.30 & 16.60.

I increased the Point 2 calibration value from 20.050 to 20.075, wrote the value to the controller, then cycled the key OFF to ON, engine OFF and read the AFR gauge: 13.30 & 16.70.

I decreased the Point 2 calibration value from 20.075 to 20.0625, wrote the value to the controller, then cycled the key OFF to ON, engine OFF and read the AFR gauge: 13.30 & 16.70.

I decreased the Point 2 calibration value from 20.0625 to 20.055, wrote the value to the controller, then cycled the key OFF to ON, engine OFF and read the AFR gauge: 13.30 & 16.70.

I locked the calibration tables, shutdown the TunerStudio app, disconnected the cable from the ECU and turned the key OFF.

I was now very close to the Point 2 calibration value where the second 5 sec displayed value toggled between 16.60 and 16.70.

To recap: For my MegaSquirt2 ECU and 14Point7 Spartan 2 O2 sensor controller + Bosch LSU 4.9 wideband O2 sensor, I maximized the accuracy of the AFR reported value with the AFR calibration table using Custom Linear WB, Point 1 (0 Volts) = 10.0435152 and Point 2 (5 Volts) = 20.055 giving a displayed value during the first 5 sec reference check of 13.30 (ideal target = 13.328) and a displayed value during the second 5 sec reference check of 16.70 (ideal target = 16.66).