Modes of Operation

Fig. 151 Electronic Control Unit Inputs and Outputs (PGM-FI Engine):

These vehicles are equipped with an Electronic Control Unit (ECU) which uses inputs from various sensors to tell it under what conditions the engine is running. It then processes these signals and by its output to the engine control devices, the ECU controls the output of harmful emissions while still giving good engine performance under virtually all conditions.

The Air Intake System supplies air for all engine needs. It consists of the air cleaner, air intake pipe, throttle body, Electronic Air Control Valve (EACV), fast idle mechanism, and intake manifold. A resonator in the air intake pipe provides additional silencing as air is drawn into the system.

The Emission Control System and the ECU work together to regulate and reduce the amount of pollution emitted. The system includes a three-way catalytic converter, exhaust-gas recirculation (EGR) system, crankcase ventilation system, and evaporative control system.

The Idle Control System regulates the idle speed of the engine during cold start conditions, and under the normal operating conditions when the automatic transmission is in gear, A/C is on or any of the other load conditions placed on the engine at idle.