This page contains starting values, function of RCal - subpage of GenBoard/Manual/WBSensor
MembersPage/PhatBob/UserGuide explains Calibrating the WB02 sensor.
The LSU4.2 sensor male connector housing has a resistor (min-max is 35-300 Ohm, but usually 90-190 Ohm): measure resistance between rcal=pin2 and pump+ = pin6. (rcal=pin5 and pump+ = pin1 for LSU4.9 and possibly >300 Ohm resistance).
This is not a replacement for free-air calibration, just gives a starting (ballpark) value, but starting from some low calibration=50..130 value is just as good (increase gradually to show 20.9% O2).
Practical starting point from Rcal Ohm measurement:
- RCal (Ohm), wbo2 calibration starting value (and absolute minimum value)
- 30 0 (0)
- 50 62 (60)
- 70 105 (102)
- 90 149 (133)
- 100 164 (145)
- 110 179 (157) (slope in this range is appr. +1/ Ohm )
- 120 186 (167)
- 130 193 (176)
- 200 228 (220)
- 300 255 (252)
These are decimal values. These are speculation, not measurement.
Some statistics from actual calibration - show that higher calibration value is needed than the above table suggests
- Rcal=113 Ohm, wbo2_calibration=BC (188) Karkus Audi
- wbo2_calibration=B8 (184) MembersPage/MarcellGal/EngineSwap TODO: measure RCal, IIRC 116 Ohm
- for Rcal=129 Ohm, wbo2_calibration=BD (189) MembersPage/GolfGtiLpg
- wbo2_calibration=CB (203) MembersPage/MarcellGal/PowerAndTraction TODO: measure RCal, IIRC 135 Ohm
- ... add more measurement / calibration !
Free air calibration
The calibration parameter above should be fine tuned in free air without the sensor installed. In free air the LCD(or terminal Manmde02mll)O2% should read 2095 which is 20.95%. After the sensor is warmed up you can adjust the wbo2_calibration parameter up or down to increase or decrease the reading being displayed. For a sanity check it is good to let the sensor cool down and warm back up to make sure the reading is still at 2095.
Breath Test
After configuring the above free air reading, you can breath on the sensor and see the 02% go down 100-200 counts(1-2%) to varify that all is working well