K 3500 Truck 4WD V8-454 7.4L VIN N TBI (1995)
Oxygen Sensor: Testing and Inspection
VISUAL INSPECTION:
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Connectors and wires
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Housing and insulator for cracks/damage
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Sensor tip for silicone contamination (white powdery coating)
PERFORMANCE TEST: Checks working range and response (speed).
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Warm engine
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Install DVOM between sensor and ground (2 volt D.C. range)
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"RUN" engine at steady cruise speed (about 2500 rpm)
Voltage should vary at least eight times in ten seconds between 0.2 and 0.8 volts (normal range).
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Drive system rich: The use of a properly adjusted propane flow-meter (J-26911) is industry standard.
Voltage should increase to at least 0.8 volts within two to three seconds.
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Drive system lean: Create a vacuum leak from a source that is not an ECM input or output.
Voltage should drop to at least 0.3 volts within two to three seconds.
NOTE: After each test the O2 sensor should return to normal operating range within two to three seconds.
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O2 Sensor should be replaced for failure to pass any of the tests above.
NOTE: A CEC system that is operating excessively rich or lean will drive the 02 sensor to its maximum range and should be repaired first
and not diagnosed as a 02 sensor failure.
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Reconnect all hoses and electrical connectors. Clear all codes set and retrain idle.
