Other Control Functions

When the engine is started, the PCM and injector control module provides a rich mixture by increasing fuel injector duration.

• When the ignition switch is initially turned on, the PCM supplies ground to the PGM-FI main relay that supplies current to the fuel pressure regulator shut-off solenoid valve/fuel tank internal solenoid valve for two seconds to pressurize the fuel system.
• When the engine is running, the PCM supplies ground to the PGM-FI main relay that supplies current to the fuel pressure regulator shut-off solenoid valve/fuel tank internal solenoid valve.
• When the engine is not running and the ignition is on, the PCM cuts ground to the PGM-FI main relay which cuts current to the fuel pressure regulator shut-off solenoid valve/fuel tank internal solenoid valve.

• During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at speeds over 1,000 RPM.
• Fuel cut-off action also takes place when engine speed exceeds 6,900 RPM, regardless of the position of the throttle valve, to protect the engine from over-revving.

When the PCM receives a demand for cooling from the air conditioning system, it delays the compressor from being energized, and enriches the mixture to assure smooth transition to the A/C mode.

When EGR is required for control of oxides of nitrogen (NOx) emissions, the PCM controls the EGR valve.

The system controls the voltage generated at the alternator in accordance with the electrical load and driving mode, which reduces the engine load to improve the fuel economy.