Crossfire SRT-6 V6-3.2L SC VIN N (2005)
uses pulse width modulation to control the ground side of the heater to regulate the temperature.
UPSTREAM OXYGEN SENSOR
The input from the upstream heated O2 Sensor tells the PCM the oxygen content of the exhaust gas. Based on this input, the PCM fine tunes the air-fuel
ratio by adjusting injector pulse width.
The sensor output varies from 0 to 1 volt, depending upon the oxygen content of the exhaust gas in the exhaust manifold. When a large amount of
oxygen is present (caused by a lean air-fuel mixture), the sensor produces voltage as low as 0.1 volt. When there is a lesser amount of oxygen present
(rich air-fuel mixture) the sensor produces a voltage as high as 1.0 volt. By monitoring the oxygen content in the exhaust gases and comparing that to the
oxygen content in ambient air and converting it to electrical voltage, the sensor acts as a rich-lean switch. The heating element in the sensor provides heat
to the sensor ceramic element. Heating the sensor allows the system to enter into closed loop operation sooner. Also, it allows the system to remain in
closed loop operation during periods of extended idle.
In Closed Loop, the PCM adjusts injector pulse width based on the upstream heated oxygen sensor input along with other signals. In Open Loop, the
PCM adjusts injector pulse width based on preprogrammed (fixed) values and inputs from other sensors.
DOWNSTREAM OXYGEN SENSOR
The downstream heated O2 Sensor signal is used to detect catalytic convertor deterioration. As the convertor deteriorates, the signal from the
downstream sensor begins to match the upstream sensor signal except for a slight time delay. By comparing the downstream heated oxygen sensor signal
to the signal from the upstream sensor, the PCM calculates catalytic convertor efficiency. This calculation is also used to establish the upstream O2 goal
voltage (switching point).
