5. Operation
Once the LM-1 has been installed and is in place (see Chapter 4: Installation), lambda
measurements can be taken.
In operation the meter's display shows:
Showing the current lambda value and air-fuel-ratio. The numeric lambda and air-fuel-ratio values
are averaged over about 0.2-0.3 seconds so that the numbers are more consistent and easy to
read.
If lambda is bigger than 6 (example free air), the display shows the oxygen content of the
measured gas instead of AFR.
The bar-graph at the bottom shows the actual instant lambda value in 16 steps. The more of the
bar showing, the richer the mixture. The bar at mid-level means a lambda value of 1.0 (AFR of
14.7 for gasoline). If the whole bar shows, the actual lambda value is 0.68 or richer (AFR of 10 or
less for gasoline). If none of the bar shows the lambda value is 1.32 or leaner (AFR 19.4 or more
for gasoline).
6. Calibration
To achieve maximum precision the LM-1 and its sensor needs to be recalibrated frequently.
When the measured lambda is bigger than 6, the display will show the oxygen content of the
measured gas in %. For free air it should show 20.9%. If the display value is different by more
than 0.6%, recalibrate. You can test the oxygen sensor by breathing on it. The oxygen content of
your breath will show.
The sensor MUST be operated in free air for calibration.
If the wide-band sensor is installed in a vehicle, wait 6-8 hours after running the engine so that all
exhaust gas is dissipated from the exhaust tract of the vehicle. Otherwise, disengage the oxygen
sensor and expose the sensor to air (away from the exhaust) for calibration purposes
1. Connect the meter to 12V from the vehicle and switch it on.
2. When the sensor is warmed up, quickly press and release the
'Calibrate'
button.
3. After the calibration is complete, switch the LM-1 off and wait for 30 seconds before you start
the car.
The display will show "Free Air Calibr." while it calibrates itself. When the calibration procedure is
finished (2-3 seconds) the display returns to normal showing lambda and oxygen content. If the
oxygen content now differs from 20.9% by more than 0.6%, repeat the calibration.
When the sensor is changed – either with a replacement sensor or a new type of sensor --, the
heater circuit of the LM-1 needs to be recalibrated as well. Follow the steps in chapter 3 'First
Time use'. The heater calibration data in the LM-1 will be reset when the meter is operated from
12V without a sensor connected for at least 2 seconds.
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