Summit L4-1597cc 1.6L DOHC (1990)
Oxygen Sensor: Description and Operation
The oxygen sensor measures the level of oxygen in the exhaust after combustion, which is directly proportional to the air/fuel mixture. In order for the
sensor to get an accurate reading, it is threaded into the exhaust manifold or pipe ahead of the catalytic converter.
Oxygen Sensor
The sensor is made of zirconium dioxide (a ceramic material), with the inner and outer surfaces being coated with a very thin layer of platinum. The
outer surface is exposed to the stream of exhaust gasses, while the inner surface is exposed to outside air. The difference between the amount of oxygen
contacting the inner and the amount of oxygen contacting outer surface, causes a voltage to be generated. Voltage output fluctuates from zero to one volt
DC. The number of sensor fluctuations (lean-rich-lean) within one minute are called cross-counts.
Once the Oxygen Sensor has reached its operating temperature, and begins its cross-counts, the Control Unit will begin to make adjustments to the
injector pulse widths. As the intake air/fuel mixture moves from rich (0.9) to lean (0.1), the oxygen sensor output voltage decreases. A signal is generated
and sent to the Control Unit. Again adjustments are made and the air/fuel ratio is enriched.
