4.1. General information
All engines except for early models (518), are equipped with electronic system of injection of fuel.
Early models 518 are equipped with Solex carburetors. It is applied or the Solex 2B4 carburetor (early models), or 2 (late models). The mechanical fuel pump is put in action by an ekstsentrikovy cam of a camshaft.
Models with injection of fuel are equipped or fuel system of injection of L-Jetronic, or Motronic. Since 1988 of model with injection of fuel are equipped with Motronic system applied so far - this system easy to distinguish from earlier on lack of an injector of cold start. The electric fuel pump is located under a back of the car or in a fuel tank. The relay of the fuel pump on Motronic system turns on low level of a signal from the Motronic (ECV) control unit. The fuel pump after inclusion of ignition turns on for some seconds and further works only at operation of the engine.
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 and the throttle case (model with injection) and the inlet pipeline. In this Chapter all components, except for the inlet pipeline are considered; for data on removal and installation of the inlet pipeline address to the Part the Repair work which is carried out without extraction of the engine from the car.
The throttle valve in the case of a throttle is put in action by an accelerator cable. By pressing an accelerator pedal the butterfly valve opens and the air stream in system increases.
In systems of injection of fuel the zaslonka in the batcher of air opens more widely and the stream of air increases. The sensor of provision of the throttle, established on a zaslonka axis, measures a corner of provision of a zaslonka (as far as it opens) and will transform this size to tension which is transferred in the computer.
On carburetor models the fuel pump submits to the carburetor fuel under pressure.
The needle valve in the poplavkovy chamber supports constant level of fuel. On channels of return of fuel system surplus of fuel arrives back in a fuel tank.
On models with fuel injection the electric fuel pump submits fuel to the highway with constant pressure. The electric fuel pump on late models is located in a fuel tank or near a tank on early models. Early models are also equipped with the intermediate pump located in a fuel tank. The intermediate pump operates as auxiliary more powerful main pump at creation of necessary pressure. Pressure in fuel system the regulator of pressure of fuel operates. The fuel system also has a damper of pulsations of pressure close to the fuel filter. The damper reduces the pulsations of pressure caused by operation of the fuel pump and opening - closing by an injector. The amount of fuel injected into ports of an admission precisely is defined by the electronic Control unit (ECV or the computer). Some late models 5 of a Series have the device of cooling of fuel in the return line.
Electronic control system (system of injection of fuel)
Except serial opening of injectors as it is described above, the electronic control unit carries out some other the tasks connected with control of fuel system and system of release. The block carries out these tasks, using data which arrive from a large number of the information sensors located in an impellent compartment, comparing these data with information in memory and changing power setting, operating various devices. The majority of works on diagnostics of malfunctions and to repair of an electronic control system due to the need in the special equipment are outside of possibilities of the mechanic - the fan. Additional data and procedures of testing of components of system of release (the sensor of concentration of oxygen, the sensor of temperature of a cooler, EVAP system and others) are given in Head of the Control system by the engine and decrease in toxicity of the fulfilled gases.