ECM LambdaCAN Series, Инструкция по эксплуатации

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5
Calibration of the Lambda Sensor
Lambda sensors operate on a diffusion mechanism. Molecules leaving the combustion
chamber diffuse through a passage into the sensor where oxidation, oxygen liberating, and
oxygen pumping occurs. The diffusion passage is like a filter and like a filter it can get
clogged. In fact, it is impossible for the passage not to get clogged when the sensor is being
used. This clogging of the diffusion passage is the main mechanism by which a sensor
“ages” resulting in a calibration shift.
All Lambda sensors are calibrated (i.e. spanned) before leaving the factory. It is
recommended that they be calibrated periodically during use. How often can only be
determined by your experimentation. Alternatively, the sensors can be sent to ECM for
recalibration.
Calibration information (both factory calibration and user calibration) for the Lambda sensor
is stored in a memory chip in the sensor’s connector. Therefore, the sensor does not have to
be used with the module it was calibrated with. Once calibrated, the sensor can be sent to
another site to be used. After use, the sensor can be returned to the calibration center for
recalibration thus compensating for any sensor aging. Centralization of calibration in this
way improves measurement consistency and extends useful sensor life.
Calibration of the Lambda Sensor and the Delta Tables
The “Span O2” task is used to calibrate the Lambda sensor. This task calibrates both the
%O2 and Lambda (AFR, FAR, PHI) measurements from the sensor. To perform an O2 span:
1. The sensor should on for at least 20 minutes. Most of the time, you only need to wait
2 minutes but some sensors, due to condensed material on them, take longer to
stabilize.
2. Put the sensor and the pressure sensor (if equipped) in ambient, stationary air. The
pressure during calibration is required if the sensor’s %O2 and Lambda (AFR, FAR,
PHI) measurements are to be pressure compensated.
3. Calculate the %O2 in the air. The %O2 in air with no humidity is 20.945. This
percentage decreases with increasing humidity. To calculate the %O2 in non-zero
humidity air, use the “Calculate %O2 in Air” tool in the Configuration Software or
Appendix C. 20.7 is a common number.
4. Select O2 as a TPDO parameter.
5. Select the Task “Span O2”. Enter the displayed (as the TPDO) O2 and the actual
%O2 (as calculated in 3 above), then click on “Span”.