PGM-FI Control System

System Description

Injector Timing and Duration
The ECU contains memories for the basic discharge durations at various engine speeds and manifold pressures. The basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors to obtain the final discharge duration.

Electronic Air Control
Electronic Air Control Valve (EACV)
When the engine is cold, the A/C compressor is on, the transmission is in gear (A/T only) or the alternator is charging, the ECU controls current to the EACV to maintain correct idle speed.
Ignition Timing Control
•   The ECU contains memories for basic ignition timing at various engine speeds and manifold pressures. Ignition timing is also adjusted for coolant temperature.
Other Control Functions
1. Starting Control
When the engine is started, the ECU provides a rich mixture.
2. Fuel Pump Control
•   When the ignition switch is initially turned on, the ECU supplies'ground to the main relay that supplies current to the fuel pump for two seconds to pressurize the fuel system.
•   When the engine is running, the ECU supplies ground to the main relay that supplies current to the fuel pump.
•   When the engine is not running and the ignition is on, the ECU cuts ground to the main relay which cuts current to the fuel pump.