ENGINE
<NON-TURBO>
-
Control System
I-21
The crankshaft position sensor mounts to the engine block behind the generator, just above the oil filter.
AFU0073
HEATED OXYGEN SENSORS
As vehicles accumulate mileage, the catalytic con-
vertor deteriorates. The deterioration results in a
i
less efficient catalyst. To monitor catalytic convertor
deterioration, the fuel injection system uses two
heated oxygen sensors. One sensor upstream of
the catalytic convertor, one downstream of the con-
vertor. The powertrain control module (PCM)
compares the reading from the sensors to calculate
the catalytic convertor oxygen storage capacity and
efficiency. Also, the PCM uses the upstream heated
oxygen sensor input when adjusting injector pulse
width.
WIAKWAA
When a deteriorating catalyst’s efficiency drops be-
low emission standards, the PCM stores a diagnostic
trouble code and illuminates the malfunction indica-
tor lamp (MIL).
The MFI relay (automatic shut down relay) supplies
battery voltage to both the upstream and down-
stream heated oxygen sensors. The oxygen sensors
are equipped with a heating element. The heating
element keeps the sensors at proper operating tem-
perature during all operating modes.
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