The system of injection of fuel represents the difficult device with many elements. Its diagnostics and repair requires the special equipment, use of difficult multistage techniques and considerable practical experience. Therefore it is the best of all to charge diagnostics and repair to the specialized service stations and car repairs of Volkswagen having for this purpose the special equipment.

System of the central injection  of Mono-Jetronic fuel

Fig. 5.23. System of injection Mono-Jetronic: 1 – fuel pump; 2 – fuel tank; 3 – fuel filter; 4 – nozzle; 5 – air flowmeter; 6 – control unit; 7 – proofreader of idling; 8 – potentiometer of a butterfly valve; 9 – relay; 10 – the ignition switch, 11 – the accumulator; 12 – butterfly valve; 13 – ignition distributor; 14 – engine temperature sensor; 15 – lambda sensor; 16 – pressure regulator

The system of injection of Mono-Jetronic fuel provides electronic faltering injection of gasoline in an inlet collector. At the same time the Mono-Jetronic system unlike systems of injection Digifant and K-Jetronic has one is central the located nozzle of 4 (fig. 5.23) for all cylinders. Distribution of fuel in separate cylinders happens, as in engines to the carburetor, – through an inlet collector. Air is soaked up by the engine via the air filter and gets to the injection device. In the case of an injector there is a butterfly valve operated by a flexible cable 12. The angle of opening of a butterfly valve is fixed by a potentiometer of the 8th butterfly valve, and transmits a signal to the control unit 6, depending on instant value of turns of the engine and defines amount of the soaked-up air.

The control unit regulates by the measured amount of air and data on the frequency of turns of the engine from system of ignition the moment and the number of injection. The longer the nozzle is open, the amount of injectable fuel is more.

Additional sensors are responsible for correctly measured amount of fuel in the different modes of the movement.

The potentiometer of the 8th butterfly valve reports to the control unit 6 about the provision of a butterfly valve idling.

The control unit slightly opens or covers through a servomotor, a butterfly valve and thus supports stable turns of idling.

The sensor of temperature 14 on a connector of cooling liquid takes engine temperature.

The air temperature sensor in the reception channel takes air temperature.

The lambda sensor 15 measures the content of oxygen in a stream of exhaust gases. The control unit, on its signal, supports the content of harmful emissions in exhaust gases at the lowest level.

At cars with the catalyst the composition of exhaust gases is supported at the level providing the best reburning in the catalyst.

Fig. 5.24. An arrangement of elements of system of injection of Mono-Jetronic in a motor compartment: 1 – injector; 2 – temperature regulator; 3 – ECU control unit; 4 – fuel nozzle; 5 – fuel pressure regulator; 6 – the socket of a heater of the air coming to the engine; 7 – control bulb; 8 – vacuum adjustment of a corner of an advancing of ignition; 9 – potentiometer of a butterfly valve; 10 – socket lambda sensor; 11 – water reflector of a potentiometer of a butterfly valve; 12 – sensor of temperature of system of injection (blue); 13 – a heater thermoswitch in an inlet collector (red), 14 – a potentiometer of provision of a butterfly valve; 15 – air temperature sensor; 16 – the electromagnetic valve of the filter with absorbent carbon (gray); 17 – electromagnetic valve; 18 – additional resistor of an injector; 19 – electric socket of a potentiometer of provision of a butterfly valve; 20 – throttle shock-absorber

The arrangement of elements is shown in fig. 5.24 .

System of the central injection  of Mono-Motronic fuel

The system of injection of Mono-Motronic fuel unlike Mono-Jetronic is executed in one block. Thanks to combination of system of ignition with system of injection, ignition works under various operating conditions of the engine better. The majority of the carried-out works and instructions for the Mono-Jetronic system concern as well Mono-Motronic.

Electronics of the monitor registers malfunction in system of injection. This malfunction after the first emergence, registers in memory. At the same time on an additional guard the control bulb lights up, signaling that malfunction is written down. If malfunction arises only once, for example at unreliable contact, then she all the same registers in memory of the monitor.

System of the distributed  Digifanf fuel injection

Fig. 5.25. System of injection of fuel: 1 – fuel tank; 2 – fuel pump; 3 – fuel filter; 4 – fuel distributor; 5 – pressure regulator; 6 – control unit; 7 – nozzle; 8 – nozzle of start of the cold engine; 9 – screw of adjustment of turns of idling; 10 – potentiometer of provision of a butterfly valve; 11 – butterfly valve; 12 – air flowmeter; 13 – temperature sensor; 14 – thermotime sensor; 15 – ignition distributor; 16 – regulator of turns of idling; 17 – accumulator; 18 – ignition lock; 19 – relay

The system of injection of Digifant fuel is developed by VW and is established on engines with alphabetic reference of PB, PF, PG and 2E. The block 19 (fig. 5.25) exercises control of ignition and injection at the same time. The injecting part generally corresponds to the L-Jetronic system of BOSCH. The system of injection of Digifant fuel injects fuel into an inlet collector in front of each inlet valve. Unlike Mono-Jetronic the Digifant system has a separate nozzle for each cylinder.

Fuel gets from the fuel tank 1 electric fuel pump 2 and via the fuel filter 3 moves through the fuel highway to nozzles 6, 10.

The regulator of pressure of the 4th fuel highway monitors constant maintenance of pressure in fuel system.

The quencher of fluctuations in the regulator of pressure 4 reduces fluctuations of pressure in the fuel return pipeline.

Air is soaked up by the engine via the air filter, an inlet collector and its volume measured by a flowmeter of the 15th stream of air.

In the case of a flowmeter of air there is a gate which when passing an air stream deviates. The corner of a deviation of the gate serves as an air stream measure. From a potentiometer on a gate axis the signals corresponding to position of the gate come to the control unit.

The control unit 19 regulates time and amount of injectable fuel according to the measured amount of air and frequency of turns of the engine. The longer the nozzle is open, the more fuel is injected. Additional sensors allow to dose precisely fuel in the different operational modes.

The distributor of fuel 5 stabilizes idling turns, especially during warming up of the engine or if the engine is loaded by the included electric consumers.

The potentiometer of the 18th provision of a butterfly valve is located directly on a shaft of a butterfly valve 12. It signals the control unit about the provision of a butterfly valve at turns of idling and full capacity. It concerns control of the fuel supply switch as contacts the regulator of 13 turns of idling are still closed, at the turns of the engine exceeding 1500 min.-1 (compulsory idling), the control unit has to stop supply of fuel in the engine.

The lambda sensor, installed in cars with the adjustable catalyst, measures the content of oxygen in exhaust gases and sends the corresponding electric signals to the control unit. The control unit changes quality of air-fuel mix so that exhaust gases were in the best way burned up in the catalyst. If the sensor participating in regulation process fails, the control unit switches to the emergency program, interfering thereby with breakage of the engine, but, allowing to continue the movement. At the same time ignition changes on more later and the power and acceleration performance of the engine falls.

Fig. 5.26. An arrangement of elements of system of injection of Digifant in a motor compartment: 1 – case of a butterfly valve; 2 – TSZ-H ignition switchboard; 3 – idling switch; 4 – control unit; 5 – switch of an open butterfly valve; 6 – valve of stabilization of turns of idling; 7 – socket lambda sensor; 8 – inlet collector; 9 – valve of adjustment of pressure; 10 – ignition coil; 11 – sensor of temperature of cooling liquid (black); 12 – the ignition distributor, 13 – the sensor of temperature of system of injection (blue); 14 – nozzles; 15 – detonation sensor; 16 – fuel distributor; 17 – the adjustment screw WITH; 18 – air filter; 19 – air stream measuring instrument; 20 – pressure regulator; 21 – screw of adjustment of turns of idling; 22 – air inlet

The provision of elements of a power supply system is shown in fig. 5.26 .

System of the distributed injection of K-Jetronic fuel

Fig. 5.27. System of injection K-Jetronic: 1 – fuel tank; 2 – fuel filter; 3 – fuel accumulator; 4 – fuel pump; 5 – rechargeable battery; 6 – ignition switch; 7 – switch of the fuel pump; 8 – ignition distributor; 9 – thermoswitch; 10 – the valve of launch of the cold engine, 11 – a spark plug; 12 – nozzle; 13 – inlet pipe; 14 – air valve of launch of the cold engine; 15 – case of a butterfly valve; 16 – butterfly valve; 17 – air consumption measuring instrument; 18 – measuring instrument plate; 19 – cap; 20 – fuel distributor; 21 – valve of warming up of the engine; 22 – fuel distributor piston; 23 – pressure regulator; 24 – measuring instrument plate lever; 25 – persistent lever of the piston of the distributor of fuel; 26 – screw of adjustment of quality (structure) of mix; 27 – screw of adjustment of amount of mix

Fig. 5.28. An arrangement of elements of system of injection of K-Jetronic in a motor compartment: 1 – pressure sensor; 2 – screw of adjustment of turns of idling; 3 – sensor of provision of a butterfly valve; 4 – TSZ-H ignition switchboard; 5 – control unit; 6 – case of a butterfly valve; 7 – ignition distributor; 8 – ignition coil; 9 – valve of stabilization of turns of idling; 10 – control unit of turns of idling and fuel supply shutdown; 11 – sensor of temperature and thermotime sensor; 12 – valve of cold start; 13 – heating valve; 14 – сапун case; 15 – nozzle; 16 – the gate of heating of the air coming to the engine; 17 – fuel distributor; 18 – the screw of adjustment of contents WITH; 19 – air filter; 20 – fuel supply shutdown valve

The system of injection of K-Jetronic fuel is a system of mechanical consecutive injection of fuel in an inlet collector in front of inlet valves. Fuel gets from the fuel tank of 1 (fig. 5.27) , the giving fuel pump and the main fuel pump 4 located in it, and moves via the fuel accumulator 3 in the fuel filter 2, to the fuel 20 distributor. The distributor of fuel distributes and gives to cylinders fuel through nozzles 12 according to amount of the measured air. Additional sensors allow to dose precisely fuel at various temperatures and service conditions (fig. 5.28) .

The fuel accumulator holds fuel under pressure a long time, even after switching off of the engine that interferes with formation of bubbles and improves start of the hot engine.

The switch of the fuel pump 7 (see fig. 5.27 ) gives current to the fuel pump 4 and the valve of 21 warmings up of the engine. The switch of the fuel pump interrupts giving of current to the pump, at switching off of ignition and lack of impulses of ignition (the engine is switched off, ignition is switched off). Besides, the switch interrupts supply of fuel at excess by the engine of the maximum turns.

At start of the cold engine the valve 10 of launch of the cold engine injects additional amount of fuel into an inlet collector, for start simplification.

The thermoswitch 9 regulates duration of injection of the valve 10 of launch of the cold engine.

The regulator of pressure 23 supports pressure in system about 470-540 kPa.

The regulator of warming up enriches mix during warming up.

The electric control unit operates valves of shutdown of supply of fuel and stabilization of turns of idling.

System of the distributed KE-Motronic fuel injection

The system of injection of KE-Motronic fuel is the combined system of ignition and injection, with the general control unit. Nozzles are mechanically arranged as and in the K-Jetronic system (see fig. 5.27 ), but in addition have electronic control. Thanks to electronics there is a management of the number of injection by means of additional sensors which more stoutly and quicker collect and process information. Besides, the lambda regulation at operation of the catalyst is facilitated. When using the KE-Motronic system need for the warming up regulator, the disconnecting valve and system of adjustment of pressure disappears.

The electronic control unit regulates a fuel dose in various operational modes of the engine via the electrohydraulic regulator of pressure which is located on the distributor of amount of fuel. It means that the monitor monitors enrichment of mix at cold start and warming up of the engine, enrichment of mix at acceleration and full capacity. Besides, it blocks access of fuel at the movement on inertia.

The membrane regulator of pressure, on the distributor of amount of fuel, supports pressure in system from 610 to 660 kPa.

The filter of absorbent carbon interferes with that harmful vapors of fuel got from the fuel tank into the atmosphere, the evaporating fuel collects in the container with absorbent carbon. At the movement of couple under control of two magnetic valves move in the engine for combustion again.

The memory device in the control unit distinguishes the appeared malfunction and writes down it. At failure of the important sensor, the control unit switches to the reserve program (using average codes) that the engine did not stop.

Fig. 5.30. An arrangement of elements of system of injection of KE-Motronic in a motor compartment: 1 – socket lambda sensor; 2 – case of a butterfly valve; 3 – control unit; 4 – a pipe of measurement of contents WITH; 5 – valve of stabilization of turns of idling; 6 – output block; 7 – ignition coil; 8 – the distributor with Hall's sensor; 9 – relay of the fuel pump; 10 – connection of the sensor, ignition advancing corner; 11 – detonation sensor socket; 12 – temperature sensor; 13 – valve of cold start; 14 – sensor of a detonation 1; 15 – injector; 16 – sensor of a detonation 2; 17 – the gate of heating of the air coming to the engine; 18 – pressure regulator; 19 – fuel distributor; 20 – coal filter; 21 – air filter; 22 – potentiometer; 23 – pressure regulator; 24 – air flowmeter; 25 – valve of the coal filter; 26 – spark plug; 27 – sensor of provision of a butterfly valve

The arrangement of elements of system of injection of KE-Motronic in a motor compartment is shown in fig. 5.30 .

Control system of the Simos engine

The device and the principle of action of a control system of the Simos engine are similar to the Digifant system.

Fig. 5.29. Arrangement of elements of system Simos engine: 1 – electromagnetic valve of a canister of charcoal; 2 – air stream measuring instrument; 3 – oxygen sensor socket; 4 – throttle case; 5 – ECU block; 6 – injector; 7 – fuel pressure regulator; 8 – ignition coil; 9 – speedometer drive sensor; 10 – detonation sensor socket; 11 – socket of a plait of wires; 12 – sensor of frequency of rotation of a bent shaft of the engine; 13 – socket of the sensor of frequency of rotation of a bent shaft of the engine; 14 – ignition distributor; 15 – sensor of temperature of cooling liquid; 16 – detonation sensor; 17 – connection with weight; 18 – the sensor of temperature of the air coming to the engine; 19 – charcoal filter

The arrangement of elements of system of injection of Simos in a motor compartment is shown in fig. 5.29 .

Precautionary measures during the work with the injection device

At removal and installation of elements of systems of injection it is necessary to follow the following rules:

– do not start the engine at unreliably connected rechargeable battery. Disconnect sockets of system of ignition and injection or connect only at the switched-off ignition. It concerns also measuring devices;

– start by means of the starting arrangement is admissible only within no more than 1 min., at a voltage no more than 16,5 V;

– do not disconnect the rechargeable battery from onboard network at the working engine, it can lead to failure of the control unit;

– before carrying out an inspection of electronic system of injection, it is necessary to be convinced of serviceability of system of ignition, it means that ignition and candles have to conform to technical requirements;

– during the work with system of injection be careful to prevent hit of dust and dirt in various components of system. It is not recommended to use compressed air or fleecy fabrics for cleaning of system.

PREVENTION During the work with mechanical parts of system of injection it is necessary to observe strict purity. Before dismantling it is necessary to wash out details gasoline. The system is under pressure. Therefore before replacement of details to reduce pressure, gradually weakening fastening on the valve of cold start.

Check and adjustment of turns of idling (XX) and quality of mix

Check and adjustment of turns of idling and quality of mix will require a tachometer and the analyzer of exhaust gases.

And quality of mix you carry out preparation for adjustment of turns of XX as follows:

– check and adjustment are carried out on the heated-up engine with correctly determined moment of ignition and serviceable system of production of the fulfilled gases;

– start the engine and leave to idle until temperature of oil reaches 80 °C. At the same time you watch that temperature of cooling liquid did not exceed normal as during check and adjustment the fan has to be switched off;

– kill the engine, disconnect everything consumers of energy (headlights, the radio tape recorder, the conditioner, etc.);

– disconnect and muffle a stopper a hose of ventilation of a case;

– connect a control tachometer and a gas analyzer;

– if fuel-supply lines were disconnected from nozzles or replaced new before check and adjustment of frequency of rotation of idling, increase frequency up to 3000 min.-1, then leave the engine to idle within 2 min. prior to check and adjustment;

PREVENTION The reason of increase in contents WITH not in adjustment, and in saturation by oil vapors from an engine case as a result of fluidifying of oil at heavy traffic on short distances. At long uniform motion on the flat area the amount of fuel in oil decreases, and contents WITH is normalized. It is also normalized after continuous (about 30 min.) the movements or after oil replacement

– the throttle zslonka has to be in the idling family way.

And quality of mix of system of injection of Digifant fuel carry out adjustment of turns of XX in the following order:

– at the switched-off ignition connect a tachometer and a gas analyzer of exhaust gases in compliance to instructions of the manufacturer;