Fuel injection and emission control systems are linked both structurally and functionally. For more information on these systems, see:. v chapter 6.
Air supply system
The air supply system consists of: air cleaner, air ducts, mass air flow sensor, throttle valve, idle speed control system and intake manifold. On V-engines, the intake manifold has a variable configuration. More information about the variable configuration manifold see chapter 6.
The throttle body is heated from below by engine coolant. This prevents it from freezing in cold weather. The throttle angle is measured by a position sensor. To regulate engine idle speed, the throttle body has a valve that controls an additional air flow directed bypassing the throttle valve. On 4-cylinder engines, this valve is located on the top side of the throttle body, and on a V-twin engine, it is located on the bottom side.
(The original text is published on www.mazbook.ru)
When the engine is idling, the idle speed control system maintains the required composition of the working mixture. This system includes the electronic control unit (ECU), a coolant temperature sensor, an auxiliary air flow control valve, and other sensors that provide information to the ECU. The idle speed control system takes into account engine operating conditions, specifically the increased engine load when auxiliary loads are activated, such as the air conditioning compressor, power steering pump, etc., as well as the engine operating temperature. The idle air control valve regulates the flow of air directed bypassing the throttle valve into the intake manifold. To facilitate starting, when turning the engine over with the starter and immediately after starting, the idle valve is fully open to supply the maximum amount of air.
Electronic control unit
Detailed information about the electronic engine management system is given in chapter 6.
Fuel injection system
The fuel injection system includes: a fuel pump, a pump relay, a fuel pressure regulator, a fuel rail and injectors.
The fuel pump, located in the fuel tank, delivers fuel through a full-flow filter to the fuel rail. At the outlet of the tank, a shut-off valve is installed, which, when the pump stops, closes the fuel line and maintains excess pressure in it. In addition, there is a bypass valve at the pump outlet, which prevents increased fuel pressure in the delivery line. It opens when the engine has low fuel consumption or if the line is blocked and passes fuel from the pump outlet back to the inlet.
A fuel pressure regulator is installed in the fuel rail, which maintains a set pressure at the fuel inlet to the injectors under any engine operating mode. Excess fuel from the pressure regulator is returned back to the tank.
The injectors have electromagnetic control with a needle valve. When a control pulse is applied to the electromagnet from the control unit, the valve needle rises and, through the opened separator, fuel under pressure from the ramp is injected into the inlet valve of the next cylinder. The cyclic fuel supply is determined by the duration of the control electrical pulse.
The fuel pump relay is located in the relay box in the engine compartment.