Idle

When the engine is at normal operating temperature, this is a CLOSED LOOP mode. When the engine is at idle, the controller receives the following inputs:

^ Air conditioning select signal
^ Air conditioning request signal
^ Battery voltage
^ Coolant temperature sensor
^ Crankshaft Position Sensor (CPS)
^ Manifold Air/fuel Temperature (MAT) sensor
^ Manifold Absolute Pressure (MAP) sensor
^ Neutral safety switch (Automatic Transmission)
^ Oxygen sensor
^ Power steering high pressure switch
^ Sync signal
^ Throttle Position Sensor (TPS)

Based on the previous input signals, the following occurs:

^ The fuel injector pulse width and injector firing sequence are controlled by the engine controller. The engine controller does this by switching the ground to the injectors OFF and ON.
^ If the engine controller receives a signal from the power steering high pressure switch, it will increase the idle speed by adjusting the Automatic Idle Speed (AIS) motor. This adjustment is made so that the engine does not die due to increased engine load.
^ The engine controller increases or decreases the ignition spark advance and ignition timing by applying and removing the ground path to the ignition module.
^ The engine controller monitors the oxygen sensor's input, and changes the injector pulse width to keep the air/fuel ratio as close to 14.7:1 as possible. As the injector pulse width is changing, the engine controller adjusts the Automatic Idle Speed (AIS) motor to keep the idle rpm at its specified setting.
^ The engine controller controls the A/C compressor clutch via the A/C clutch relay, if the driver has selected A/C and if the A/C thermostat has requested A/C.