Engine Control Module - General Operation
^
Coolant temperature sensor
^
Charge Air Temperature sensor
^
Manifold absolute pressure (MAP) sensor
^
Throttle position sensor (TPS)
^
Sync signal (in distributor)
^
Neutral Safety Switch (Gear indicator signal)
^
Air conditioning select signal (if equipped)
^
Air conditioning request signal (if equipped)
Based on the previous input signals, the following occurs:
^
Voltage is applied to the fuel injectors with the engine controller. This controls the injection sequence and injector pulse width by turning the
ground circuit to each individual injector on and off.
^
The engine controller adjusts engine idle speed through the automatic idle speed (AIS) motor and adjusts ignition timing.
^
The engine controller operates the A/C compressor clutch through the clutch relay. This is done if A/C has been selected by the vehicle
operator and requested by the A/C thermostat.
^
When engine has reached operating temperature, the engine controller will begin monitoring O2 sensor input. The system will then leave the
warm-up mode and go into Closed Loop operation.
Idle
When the engine is at operating temperature, this is a Closed Loop mode. At idle speed, the engine controller receives inputs from:
^
Air conditioning select signal (if equipped)
^
Air conditioning request signal (if equipped)
^
Battery voltage
^
Crankshaft position sensor
^
Coolant temperature sensor
^
Charge Air Temperature sensor
^
Manifold absolute pressure (MAP) sensor
^
Throttle position sensor (TPS)
^
Sync signal (in distributor)
^
Battery voltage
^
Neutral Safety Switch (Gear indicator signal)
^
Oxygen sensor
Based on these inputs, the following occurs:
^
Voltage is applied to the fuel injectors with the engine controller. This will control injection sequence and injector pulse width by turning the
ground circuit to each individual injector on and off.
^
The engine controller monitors the O2 sensor input and adjusts air-fuel ratio by varying injector pulse width. It also adjusts engine idle speed
through the automatic idle speed (AIS) motor.
