The functioning of the injection system closely intersects with the operation of the exhaust gas toxicity reduction system, more detailed information on which can be gleaned from the materials of the Chapter Engine management systems.
Air supply system
The system consists of an air cleaner, air hoses, throttle body, idle speed stabilizer and intake manifold. The cavity resonator included in the intake air duct can significantly reduce the level of noise produced by the engine.
The throttle bodies are of a single chamber design, crossflow on Civic models with D16Y5 and D16Y8 engines, and downflow on all others. The lower part of the throttle body is heated by engine coolant to prevent icing in freezing weather. The idle speed adjustment screw is located on top of the throttle body. Throttle position sensor (TPS) connected to the axis of the latter and monitors the degree of its opening.
Electronic control system
The composition and principle of operation of the electronic control system and PCM are discussed in detail in Chapter Engine management systems.
Fuel supply system
Fuel system components include: submersible electric fuel pump, fuel pressure regulator, injection injectors, fuel pulsation damper (only applies to some models) and the main relay of the injection system.
The electric fuel pump is located inside the gas tank. The pump draws fuel from the tank through the filter element, then pumps it through an additional fuel filter and delivers it to the injection injectors.
The fuel pressure regulator provides a constant pressure of fuel supply to the injectors. Excess fuel is sent back to the fuel tank through the return line.
The injectors are solenoid valves with a constant stroke. The main components of an injector are: a control solenoid, a plunger and a needle valve. All of the listed parts are placed in a common housing. When an electric current passes through the solenoid coil, the needle valve opens slightly and fuel under pressure fills the cavity of the injector body and is ejected through its nozzle. The amount of injected fuel is determined by the duration of the valve opening time, i.e., the duration of the voltage supply to the electromagnet coil.
The duration of the injectors is controlled by the PCM. The module memory contains the basic values of the valve opening time for various combinations of input parameters (engine speed and intake air). The necessary information is supplied to the module in the form of signals from various engine sensors.
The main injection system relay is mounted on the left or right in front of the windshield under the fairing panel and consists of two operating elements, one of which is the PCM and fuel injectors relay, and the second is the fuel pump relay.