Other Control Functions

When the engine is started, the ECM/PCM provides a rich mixture by increasing fuel injector duration.

• When the ignition switch is initially turned on, the ECM/PCM supplies ground to the PGM-FI main relay that supplies current to the fuel pump for two seconds to pressurize the fuel system.
• When the engine is running, the ECM/PCM supplies ground to the PGM-FI main relay that supplies current to the fuel pump.
• When the engine is not running and the ignition is on, the ECM/PCM cuts ground to the PGM-FI main relay which cuts current to the fuel pump.

• During deceleration with the throttle valve closed, current to the fuel injectors is cut off to improve fuel economy at speeds over the following rpm:
  • M/T: 1,000 rpm
  • A/T: 990 rpm
• Fuel cut-off action also takes place when engine speed exceeds 7,000 rpm, regardless of the position of the throttle valve, to protect the engine from over-revving. On an A/T model, the PCM cuts the fuel at engine speeds over 5,000 rpm when the vehicle is not moving.

When the ECM/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 the engine coolant temperature is above 154°F (68°C), the ECM/PCM controls the EVAP purge control solenoid valve which controls vacuum to the EVAP purge control canister.