Engine management system components in the engine compartment
Schematic diagram of the engine management system
Engine Management System Component Locations Part 1
Engine Management System Component Locations Part 2
Fuel is drawn from the fuel tank by an electric fuel pump and supplied through a fuel filter to the fuel rail. The pressure regulator maintains the pressure in the fuel system at the level 3.5 atm.
In engines, fuel is injected in pulses through electrically controlled injectors into the intake ports, located just before the engine's intake valves. The engine control unit (ECM) determines the optimum ignition and injection timing, as well as the amount of fuel injected, in coordination with other vehicle systems. The high voltage for sparking is generated by the ignition coils, mounted above the spark plugs, at the signal from the ECM.
The crankshaft position (CKP) sensor provides the control unit with information about the crankshaft speed and its exact position. This information is used to determine injection and ignition timing. The CKP sensor is located on the rear of the engine and works on the basis of the Hall effect, scanning the teeth of the rotor mounted on the crankshaft.
The camshaft position (CMP) sensor is located at the rear end of the cylinder head and operates similarly to the CKP sensor, scanning the toothed rotor at the end of the intake camshaft. The CMP sensor, together with the CKP sensor, is used to determine the TDC of the piston of the first cylinder, dynamically adjust the valve timing (by means of an electromagnetic valve and an intake valve phase regulator), selective control of detonation in cylinders and for determining the injection sequence.
The air required to form the working mixture is sucked in by the engine through the air filter and passes through the throttle valve and the intake manifold to the intake valves. The amount of air sucked in is regulated by a throttle valve with an electric drive, controlled by signals from the accelerator pedal position sensor. Thanks to electronic control, the mass air flow in the intake manifold can be set independently of the accelerator pedal position, and at idle speed the throttle valve opens to the angle required to set the required crankshaft speed. The volume of air sucked in is determined by the manifold pressure (MAP) sensor with a built-in intake air temperature (IAT) sensor.
The knock sensor (KS) is screwed into the side of the cylinder block and prevents the occurrence of shock combustion of the fuel. Thanks to this, the ignition timing is kept at the detonation limit, which ensures better use of fuel energy and thus reduced fuel consumption.
Information from other sensors and control voltages supplied to the actuators ensure optimal engine operation in any situation. If some sensors fail, the control unit switches to the emergency program mode to prevent possible engine damage and ensure further movement of the vehicle. In emergency mode, the injectors operate simultaneously, 2 times per working cycle.
The fuel tank ventilation system consists of a gasoline vapor absorber and an electromagnetic valve. The absorber concentrates fuel vapors that form in the tank as a result of fuel heating. During engine operation, fuel vapors are pumped from the absorber and participate in the formation of the working mixture.
Reduction of exhaust toxicity is achieved with the help of a 3-function catalytic converter and lambda probes (before and after catalytic converter).
Also, to eliminate leaks of unburned hydrocarbons into the atmosphere, a crankcase ventilation system (PCV) is used. Gases and oil vapors formed in the crankcase enter the intake manifold (due to the pressure difference - it is higher in the crankcase) and burn in the cylinders together with the fuel.
In order for the numerous electronic control units to be able to exchange data with each other, these units are connected by a high-speed CAN data bus. The CAN bus consists of two lines (H and L), which allows for a reduction in the amount of electrical wiring. Each control unit can simultaneously transmit and receive data, but each specific unit reads only the data it needs from the CAN bus.
CAN bus organization diagram
