- air supply systems for engine cylinders;
- electronic control systems;
- fuel system.
The main element of the system is the engine control unit (PCM), which, based on information from many sensors, controls the fuel injectors by changing the pulse length, i.e. the length of time the injectors are open. This ensures the preparation of an air-fuel mixture corresponding to the required operating conditions of the engine.
The air supply system to the engine cylinders consists of an air filter, pipes, a throttle assembly, an idle control system and an intake manifold. On pre-2001 models, the intake manifold and air distribution plenum are one unit.
On models since 2001, a specially designed intake manifold with flow control is installed.
The throttle assembly is a pipe with adjustable air flow through it, and serves only to control the amount of air supplied to the engine cylinders.
The lower part of the throttle assembly is heated with coolant in order to prevent its icing in winter.
The adjusting screw is located at the top of the throttle assembly. The throttle position sensor is connected to the throttle valve shaft.
When the engine is running at idle speed, the air-to-fuel ratio is controlled by the control system, which consists of the engine control unit (PCM), idle speed control valve (IAC) and other sensors (ECT, IAT, TPS, MAP, MAF), working in conjunction with an electronic fuel injection system (EFI). Idle speed control valve (IAC) activated depending on engine operating conditions (activation of the air conditioning system, operation of the power steering, outside air temperature). This valve regulates the amount of air supplied to the engine cylinders bypassing the throttle. Due to this, when the engine warms up, even with the throttle closed, air enters the engine cylinders, adjusting the idle speed. The intake manifold also reduces airflow pulsations.
The electronic control system controls fuel injection, ignition timing, diagnostic system and other systems.
The fuel system consists of the following components:
- fuel pump;
- fuel pressure regulator;
- fuel filter;
- fuel lines;
- distribution fuel line;
- nozzles.
On models before 2001, 2 fuel filters are installed: the main one is on the left side of the engine compartment, and the additional one is in the fuel pump/fuel level sensor unit.
Models since 2001 have 1 fuel filter in the fuel pump/fuel gauge assembly.
The nozzles dose and spray the fuel. When voltage is applied to the solenoid winding, the needle rises, passing fuel. The amount of fuel is determined by the duration of the pulse during which the nozzle is open.
The main fuel pump relay is located in the relay/fuse box in the engine compartment and 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.