2.18. System of injection of gasoline

Petrol VW T4 engines are equipped with system of injection Digifant VW. Advantages of system of injection of gasoline in comparison with use of the carburetor are:

  – exact dispensing of amount of fuel in any working condition of the engine with smaller fuel consumption and good running indicators;
  – reduction of toxicity of the fulfilled gases as a result of precisely measured fuel;
  – a possibility of clarification of the fulfilled gases a lambda - the adjustable catalyst;
  – self-diagnostics of the control unit of injection, owing to what – bystry finding of malfunction;
  – the system of injection is equipped with memory in which malfunctions register.

If during operation in system of injection or the engine there are malfunctions, they register in memory. The written-down malfunctions can be unpacked by means of the block of poll of memory of VW. If the system of injection or the engine work not irreproachably, then on CTO-VW it is possible to print out the list of malfunctions for their further elimination.


If the rechargeable battery is disconnected, then malfunction in memory is erased. If malfunction during the movement appears again, she registers.

The system of injection consists of almost not worn out details and practically natrebut service, the element of the air filter only filtering demands replacement each 30000 km of a run.

Essential repair and adjusting works can be performed only by means of expensive control VW blocks so similar works can be carried out only respectively equipped HUNDRED.

At work in system of injection it is necessary to follow the same rules of purity, as at the handling of system of ignition.

Works in system of injection are complicated by the short cover of a cowl limiting access to a motor compartment. Proceeding from it a radiator with a lattice and the fan just lean back forward. Tilting of a radiator is required when carrying out almost all works in system of injection and is described in subsection 2.2.


The Digifant system is developed by VW A.G. In this system management of system of ignition and system of injection is built in an electronic control unit.

Fuel gets from the fuel tank the electric fuel pump and via the fuel filter on the bottom, moves to the fuel distributor, then to the injecting valves. Pressure regulator on a distributive tube monitors maintenance in a power supply system fuel of constant pressure about 2,5 bars. The vibroquencher in the regulator of pressure reduces fluctuations of pressure in the pipeline of the return supply of fuel.

Air is soaked up by the engine via the air filter and through a branch pipe of a butterfly valve and an inlet collector comes to the engine. The provision of a butterfly valve is estimated by a potentiometer and serves for the control unit together with engine turns at present and vacuum of an inlet pipe of a measure for regulation of an air stream.

The control unit, depending on amount of the arrived air, regulates time of injection and amount of injectable fuel. What the injecting valves are longer open, the bigger amount of fuel is injected by that. Additional probes and sensors watch in special operational conditions correctly measured amount of fuel.

The valve of control of the stabilizer of idling regulates idling turns, especially during a warming up phase and if the engine is loaded with the switched-on electric devices.

The potentiometer of a butterfly valve is directly on the roller of a butterfly valve. He reports to the control unit the provision of a butterfly valve, especially idling and full capacity thanks to what there is a control of the draft switch. If the car moves without use of force of the engine by inertia, the control unit blocks access of fuel to the engine. In this case the butterfly valve is in the provision of idling, and turns of the engine lie a little higher than 1500 about / min.

The sensor of pressure is located in the control unit and connected by a hose to an inlet pipe.

Hall's sensor in the distributor of ignition informs the control unit on quantity of turns of time at present.

The valve of cold start during start of the cold engine in addition injects fuel into an inlet collector. The faulty valve of cold start creates difficulties at start of the engine (cold and hot), worsens acceleration performance and increases fuel consumption.