Chrysler 1997 Stratus Convertible RHD Service Manual page 886

14 - 32 FUEL SYSTEM
DESCRIPTION AND OPERATION (Continued)
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 inputs. In Open Loop, the PCM adjusts
injector pulse width based on preprogrammed (fixed)
values and inputs from other sensors.
The upstream oxygen sensor threads into the outlet
flange of the exhaust manifold (Fig. 9) or (Fig. 10).
Fig. 9 Upstream Heated Oxygen Sensor—2.0/2.4L
Fig. 10 Upstream Oxygen Sensor—2.5L
DOWNSTREAM OXYGEN SENSOR
The downstream heated oxygen sensor threads into
the outlet pipe at the rear of the catalytic convertor
(Fig. 11). The downstream heated oxygen sensor
input is used to detect catalytic convertor deteriora-
tion. As the convertor deteriorates, the input from
the downstream sensor begins to match the upstream
sensor input except for a slight time delay. By com-
Engines
paring the downstream heated oxygen sensor input
to the input from the upstream sensor, the PCM cal-
culates catalytic convertor efficiency.
Fig. 11 Downstream Heated Oxygen Sensor
IGNITION SENSE—PCM INPUT
The ignition sense input informs the Powertrain
Control Module (PCM) that the ignition switch is in
the crank or run position.
INTAKE AIR TEMPERATURE SENSOR—PCM INPUT
The Intake Air Temperature (IAT) sensor measures
the temperature of the intake air as it enters the
engine. The sensor supplies one of the inputs the
PCM uses to determine injector pulse width and
spark advance.
MAP/AIR The IAT sensor and Manifold Absolute Pressure PCV VACUUM NIPPLE INTAKE MANIFOLD TEMPERATURE SENSOR
(MAP) switch they are a combined sensor that attach
to the intake manifold (Fig. 12).
The IAT sensor threads into the intake manifold
(Fig. 13) or (Fig. 14).
Fig. 12 Intake Air Temperature Sensor and MAP
Sensor—2.0L
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