EFI main relay electronic fuel injection system (EFI — Electronic Fuel Injection) supplies voltage to the fuel pump. The relay is controlled by two electrical circuits. On the first circuit, control is carried out from the engine control unit (PCM), and on the second - from the ignition switch. If the engine is not started after the ignition is turned on, the PCM will turn off the fuel pump relay after 2 seconds. Later, when the engine is started, after the first pulse from the camshaft position sensor, the relay turns on the fuel pump.
nozzles are opened by PCM signals individually in the sequence of the order of operation of the cylinders. PCM controls the opening time of the injectors (pulse duration), which determines the amount of fuel supplied to the engine cylinders.
Switch on models from 1996 to 1998, converts the PCM control pulses into current pulses in the primary winding of the ignition coil. The PCM uses signals from various sensors to calculate the required ignition timing and ignition coil buildup time.
Idle speed control valve (IAC — Idle Air Control) controls the amount of air entering the engine cylinders at idle speed.
vacuum valve (VSV) fuel vapor control systems (EVAP) - a solenoid valve controlled by the PCM for cleaning the fuel carbon filter and supplying fuel vapor to the intake manifold for combustion. This valve is also called a purge control valve.