Contents: Electronically controlled fuel…↓ Intake system ↓ Electronic control system ↓ Fuel system ↓
Electronically controlled fuel injection system
The electronically controlled fuel injection system consists of three subsystems: the intake system, the electronic control module and the fuel system. To determine the required mixture quality in all engine operating modes, the system uses the engine control module (ECM) and various sensors. The system components are shown in the figure 1.1,a,b.
The fuel injection system is closely related (functionally and structurally) with exhaust gas toxicity reduction system. For more information, please visit chapter 6A.
Intake system
The intake system includes the air filter, intake ducts, throttle body, idle air control system and intake manifold. On models produced before 2000, the intake manifold is combined with the pressure chamber and is a single part. Models produced since 2001 are equipped with a specially designed intake manifold with "variable geometry." Intake manifold replacement procedures are described in the chapter 2A or 2B.
The throttle body is single-chamber, with horizontal flow. TPS (throttle position sensor) connected to the throttle shaft to monitor the angle of its opening. The lower part of the throttle body is heated by the engine cooling system to prevent icing in severe frosts. The idle speed adjustment screw is located on the top of the throttle body.
The idle air control system controls the mixture composition at idle speed by regulating the amount of air entering the engine bypassing the throttle valve, increasing or decreasing the idle speed. The system consists of the engine control module (ECM), the idle air control valve (IAC), and various sensors (coolant temperature (ETC), manifold absolute pressure (MAP), mass air flow (MAF), throttle position (TPS), etc.). The idle air control valve is controlled by the ECM depending on the engine operating mode. The ECM module receives information from sensors (throttle opening, coolant temperature, intake air pressure and temperature, power steering and air conditioning modes, etc.) and adjusts idle speed accordingly. Finally, to avoid engine instability after starting, the starting valve opens, which operates during and immediately after starting, supplying an additional portion of air to the intake manifold.
See the source on the internet resource [ToyotaMAN]
Electronic control system
A description of the operation of this system, the engine control module and sensors can be found in chapter 6A.
Fuel system
The fuel system contains the following components: fuel pump, fuel pressure regulator, fuel filter, fuel lines, fuel rail and fuel injectors. Models prior to 2000 use a fuel filter mounted on the left strut mount panel in the engine compartment and an additional coarse fuel filter mounted in the fuel pump assembly in the fuel tank. Models produced since 2001 use a single fuel filter installed in the fuel pump assembly.
The fuel pump is submersible type. Fuel enters the pump through a coarse mesh filter in the fuel receiver, then passes through the fuel pressure regulator and fuel filter into the fuel rail and is supplied to the injectors. The fuel pressure regulator maintains a constant fuel pressure at the injector inlet.
Each fuel injector consists of a solenoid coil (winding), a plunger, a needle valve, and a housing. When current flows through the coil, the shut-off needle is retracted (rises), allowing fuel under pressure to enter the injector body and be injected through the nozzle into the intake port. The amount of fuel injected is determined by the duration of valve opening (the period of time during which the winding receives power). Since the duration and moment of opening/closing of the injector determines the composition of the fuel-air mixture, the parameters of the control pulses must be very precise.
The main fuel injection control relay, located in the relay/fuse assembly in the engine compartment, supplies power to the fuel pump relay through the ignition switch. When the engine is started, the ECM controls the fuel pump in accordance with signals received from the camshaft position sensor and the ignition switch.