4.13. General information about fuel injection
The system of injection of fuel consists of three main subsystems: fuel system, system of an admission of air and electronic control system.
The electric fuel pump located in or near a fuel tank, submits fuel under pressure to the fuel highway which distributes fuel evenly between all injectors. From the fuel highway fuel is injected into the input device of an injector located under the inlet valve. The amount of fuel injected by an injector, precisely is defined by the Electronic Control unit (ECU). At engine start-up the additional injector known as an injector of cold start-up (only on L-Jetronic systems and early systems Motronic), provides giving in the inlet pipeline of additional amount of fuel.
The pressure regulator according to razryazheniye size in the inlet pipeline operates pressure in system.
The fuel filter between the fuel pump and the fuel highway filters fuel to protect system components.
System of an admission of air
The system of an admission of air consists of the case of the air filter, a measuring instrument of a stream of air, the case of a throttle, the inlet pipeline and the related air lines. The measuring instrument of an air stream hands over information in ECU. These models are equipped with a measuring instrument of a stream of flyugerny type. Measurement of an inlet stream of air is made by a potentiometer, and the sensor of temperature takes temperature of inlet air. This information helps ECU to define amount of fuel injected by injectors (duration of injection). The butterfly valve in the case of a throttle copes the driver. When the butterfly valve opens, the amount of air passing through system increases, the signal of a potentiometer increases and ECU operates injectors on increase in amount of the fuel submitted to inlet devices.
Electronic control system
The processor control system operates fuel and other systems by means of the Electronic Control unit (ECU). ECU receives signals from a set of information sensors which trace such changing parameters, as volume of let-in air, temperature of let-in air, cooler temperature, engine turns, acceleration/delay and the content of oxygen in the fulfilled gases. These signals help ECU to define the duration of injection necessary for achievement of an optimum ratio air/fuel. These sensors and operated ECU corresponding to them actuation mechanisms are located on all impellent compartment. For the further data touching ECU and its interaction with electric systems of the engine and system of ignition address to Heads System of ignition and the Control system of the engine and decrease in toxicity of the fulfilled gases.
Are applied either L-Jetronic system, or Motronic. Late models are equipped with the modern version of initial system Motronic.