The operation of the injection system closely intersects with the operation of the exhaust gas toxicity reduction system, more detailed information on which can be found in the materials of Chapter Engine management systems.
Air supply system
The system consists of an air cleaner, air hoses, throttle body, idle speed stabilization device and intake manifold. The volumetric resonator included in the intake manifold allows to significantly reduce the level of noise produced by the engine.
The throttle body is a single-chamber design, cross-flow on Civic models with D16Y5 and D16Y8 engines, and down-flow on all others. The lower part of the throttle body is heated by engine coolant to prevent icing in cold weather. The idle speed adjustment screw is located on top of the throttle body. The throttle position sensor (TPS) is connected to the throttle shaft and monitors the degree of its opening.
Electronic control system
The composition and operating principle of the electronic control system and RSM are discussed in detail in Chapter Engine management systems.
Fuel supply system
The fuel supply system components include: electric submersible 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 sucks 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 ensures a constant pressure of fuel supply to the injectors. Excess fuel is directed back to the gas tank via the return line.
Injectors are electromagnetic valves with a constant stroke. The main components of the injector are: a control solenoid, a plunger and a needle valve. All of these parts are placed in a common housing. When 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 sprayed through its nozzle. The amount of injected fuel is determined by the duration of the valve opening time, i.e., the duration of voltage supply to the solenoid coil.
The duration of the injectors' activation is controlled by the PCM. The module's memory contains basic values of the valve opening time for various combinations of input parameters (engine speed and amount of air intake). The necessary information is sent to the module in the form of signals from various engine sensors.
The main relay of the injection system is installed on the left or right in front of the windshield under the fairing panel and consists of two working elements, one of which is the PCM and fuel injector relay, and the second is the fuel pump relay.