Air is drawn into the engine through the air filter and flows through the mass flow meter (flow meter). The flow meter housing contains a thin plate heated by an electric current, which is cooled by the flow of intake air flowing around it. In order to keep the temperature of the hot plate constant, the control electronics regulate the heating current. For example, if the amount of intake air increases, the heated plate begins to cool down. In response to this, the heating current immediately increases so that the temperature of the plate remains constant. Based on the change in the heating current, the DME control unit determines the engine load mode. The control unit regulates the injection duration and thus the injected fuel quantity in accordance with the current air flow and the current crankshaft speed. More fuel is injected when the valve injector is open longer. The correct metering of the injected fuel quantity in every driving situation is ensured by signals from additional sensors.
Fuel injection is carried out sequentially in time. This means that the valve injectors are individually controlled and inject fuel into the channels in front of the engine's intake valves in accordance with the firing order of the cylinders. By selecting the start of injection in relation to the opening phases of the intake valves, the exhaust gas parameters and power can be precisely matched. The engine responds instantly to acceleration.
The throttle angle sensor is located directly on the throttle shaft. It transmits a signal to the control unit about the instantaneous position of the throttle valve. Thanks to this, in particular, the control of the fuel feed slide switch is carried out, namely: while the throttle valve is closed and at the same time the crankshaft speed exceeds a certain value, the control unit blocks the fuel supply to the engine.
The fuel pump relay is located in the relay box behind the left shock absorber arch. The relay supplies current to the fuel pump. By disconnecting the battery, the relay interrupts the current supply to the pump when the engine is not running, for example, when the engine has stalled.
The instantaneous position of the engine crankshaft and its rotation speed are determined by two inductive sensors: the rotation speed and reference signal sensor is located at the crankshaft belt pulley. The cylinder identification sensor is located at the front on the engine chain drive cover.
In vehicles with a regulated catalytic converter, two oxygen sensors measure the oxygen content in the exhaust gases and send corresponding voltage signals to the control unit. Accordingly, the control unit changes the qualitative composition of the fuel-air mixture so that the exhaust gases burn out optimally in the catalytic converter.
The idle speed control valve regulates the air flow during idle operation, bypassing the throttle valve. This ensures that the crankshaft speed remains constant regardless of whether energy consumers such as the power steering pump or the air conditioning compressor are switched on.
The electromagnetic valve of the fuel tank ventilation system is controlled depending on the engine operating conditions. The gasoline vapors formed in the fuel tank are accumulated in a container with activated carbon and through the valve enter the cylinders and burn. Due to this, only a small amount of harmful substances enters the atmosphere and, in addition, fuel is saved.
The automatic camshaft position control system, called VANOS for short, thanks to the pressure in the main oil line, rotates the intake camshaft relative to the sprocket, depending on the speed of rotation of the crankshaft and engine load, so that optimal valve timing is ensured in terms of improving comfort when idling, the nature of changes in torque and fuel consumption. The DME system regulates the flow of oil to the VANOS actuator by means of a solenoid valve.
Ignition voltage control system when ignition voltage is too low (for example, due to damage to high voltage wires) disables the DME system, making it impossible to start the engine. This avoids damage to the catalytic converter.
Communication with other control units (ABS, NPP, automatic transmission control unit) is carried out using a special CAN data bus. This system, among other things, has the advantage that the engine wiring harness has fewer wires, and the car is less likely to break down due to failure of individual control units.