Audi 80/Avant (B4)

since 1991-1995 of release

Repair and car operation

Audi 80/Avant
+ Technical specification
+ Engines
+ System of production of the fulfilled gases
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and airintaking channels
- Injection system
   + System of injection of Mono-Motronic
   - System of injection of Digifant
      Operating procedure
      Malfunctions and independent diagnostics
      Independent repair
      Visual check
      Check of separate elements
      Removal of vpryskny nozzles
      Check of a mode of idling and analysis of exhaust gases
      List of malfunctions
   + System of injection of KE-III-Jetronic
   + Systems of injection of MPI and MPFI
+ Coupling
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrosystem
+ ignition System
+ Lighting
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
+ Specifications

Check of separate elements

Pressure regulator

At the left: the regulator of pressure of supply of fuel (shooter) is connected with the case of throttle knot a vacuum hose. It regulates pressure in system by means of the increased or reduced outflow of gasoline back in a fuel tank.

On the right: the provision of a butterfly valve is reported to the control unit by a potentiometer of a butterfly valve (3). Above on the case of a throttle hub (2) the lever of a butterfly valve (1) in which the cable of a drive of "gas" is strengthened is located.

Measurements of pressure demand existence of the corresponding manometer (V. A. G 1318) with the locking crane and the adapter. In an idling mode pressure of supply of fuel should make about 2,5 bar, at removed from a pressure regulator a vacuum hose it should raise to the 3rd bar.

Check of a potentiometer of a butterfly valve


  1. To disconnect the tip of a potentiometer of a butterfly valve.
  2. To connect an ohmmeter on contacts 1 and 2.
  3. To move a butterfly valve, thus to watch an ohmmeter. Resistance should change evenly. At the left: vpryskny nozzles (shooter) are located on right in the movement direction to the party of a head of the block of cylinders in an inlet collector.

Check of vpryskny nozzles

On the right: on an illustration the connecting tip (1) is removed from a vpryskny nozzle (2). With the light-emitting diode voltmeter it is possible to check, whether as it should be power supply of vpryskny nozzles.

For electric checks it is required to you light-emitting diode вольметр.


  1. Power supply check: one by one to remove tips on vpryskny nozzles.
  2. To connect the voltmeter to contacts of the removed tip.
  3. The assistant should get the engine.
  4. Light-emitting diodes should замерцать, otherwise there is a defect in conducting to nozzles or the control unit is faulty.
  5. Check of nozzles: to remove all tips on vpryskny nozzles.
  6. To connect an ohmmeter to both plug contacts of the first vpryskny nozzle.
  7. Standard indicator: 15 — 20 Ohm.
  8. To repeat check on other nozzles.
  9. More detailed check (tightness/type of a stream)
  10. To remove vpryskny nozzles together with a distributor pipe – the description of works see below in this chapter.
  11. However tips of wires should remain put on, and toplivoprovodny hoses connected.
  12. At the left in a branch pipe of system of cooling to remove tips of the starting valve and the temperature sensor.
    To send vpryskny nozzles to four measuring capacities.
  13. Now the assistant should scroll a starter within several seconds: all four nozzles should have an identical vpryskny stream. In this case type of a stream as it should be.
  14. To remove the central tip of vpryskny nozzles in cable mine.
  15. To switch off ignition and to include on 5 with: from each nozzle no more than two drops should act. In this case tightness of nozzles as it should be.

Check of sensors of temperature

On this chart indicators of the sensor of temperature of okhladayushchy liquid and indicators of the sensor of temperature of arriving air are represented.


  1. Sensor of temperature of inlet air: to separate the 4-contact tip from above on an air flowmeter.
  2. To connect an ohmmeter to both external shtekerny contacts.
  3. The sensor of temperature of cooling liquid: to disconnect the dark blue tip from the sensor in a bulk branch pipe of system of cooling.
  4. To connect to plug contacts of the sensor an ohmmeter.
  5. Both sensors: to remove resistance indicators.
  6. According to the chart below on the right to check, whether there are data for resistance of sensors, and also air temperature and cooling liquid at the moment of measurement within a curve.
  7. If it so, means, sensors as it should be.

Starting valve

The starting valve (shooter) is located in well available place behind on the right on a final collector.


  1. To disconnect tips from all vpryskny nozzles.
  2. Power supply: to remove a wire tip on the starting valve.
  3. To connect to the tip the light-emitting diode voltmeter with auxiliary conducting.
  4. To disconnect the tip from the sensor of temperature of cooling liquid.
  5. The assistant should turn a starter the engine, thus a light-emitting diode should flash on 1–4 villages.
  6. If it does not occur, means, conducting is interrupted, or the control unit of system of injection of Digifant is faulty.
  7. Action check: tips of nozzles remain still disconnected.
  8. To turn off the starting valve, tips of wires and a tube топливопровода remain connected.
  9. To disconnect the tip from the sensor of temperature of cooling liquid.
  10. To send the starting valve to any capacity.
  11. Ask the assistant to turn the engine a starter.
  12. During 1–4 about the valve should inject gasoline a uniform stream.
  13. Clean to wipe the valve for tightness check.
  14. Within a minute from it gasoline should not act, the starting valve outwardly also should not make impression wet from fuel.

Lambda probe

The arrow indicates plug connection to a lambda probe.

For this check the device is necessary for contents measurement WITH so it is possible, it is necessary to visit a workshop. For the correct control the system of production of the fulfilled gases should be serviceable, and a lambda probe should receive power supply (whether as it should be safety locks?).


  1. To warm up the engine.
  2. To connect the device for contents measurement WITH.
  3. To get the engine and to leave to idle within at least 2 minutes.
  4. To increase frequency of rotation to 2000 rpm.
  5. To write down the contents WITH.
  6. On the case of throttle knot to remove a vacuum hose of a regulator of pressure and to close a tubule a finger.
  7. The contents WITH for short time should raise, and then again fall to already measured size.
  8. If value WITH does not change, to separate shtekerny connection to a lambda probe.
  9. To connect a wire contact on the tip (to the control unit) in turn to the positive and negative plug of the accumulator.
  10. If at this check the indicator WITH changes, means, is faulty a lambda probe.
  11. If value of the contents WITH remains invariable, it is necessary to check conducting to the control unit.
  12. If there are no malfunctions, means, the control unit is faulty.

Air flowmeter

The locking valve (shooter) seen in an air aperture of a flowmeter of air, should move slightly. Electric check расходометра air is carried out on connecting contacts which on this illustration are visible above on the case of a flowmeter of air.

On an illustration the air line (2) which has been removed in the case of the air filter is shown to make more appreciable the sensor of temperature of air (1). It is located a little further behind in the case of a flowmeter of air screwed here.


  1. To remove a wire tip on an air flowmeter.
  2. Numbering of uvulas of contacts at the sight of from above goes from left to right from 1 to 4.
  3. Potentiometer: to connect an ohmmeter between average contacts 2 and 3.
  4. To move the locking valve, watching thus an ohmmeter.
  5. Resistance should change.
  6. To connect an ohmmeter between contacts 3 and 4.
  7. Value of resistance should be between 0,5 and 1 kiloohm.
  8. If you at measurement received other indicators, it is necessary to replace an air flowmeter.

Idling stabilization


  1. To include ignition – the valve should make an easy hooting sound. Besides, you can feel its easy vibration.
  2. Otherwise it is necessary to check safety locks.
  3. If all safety locks as it should be to remove the tip on the valve of stabilization of frequency of rotation of a shaft of the engine in an idling mode. With a diode control bulb to check food existence in the tip on contact of a black-dark blue wire (at the included ignition). For this purpose other contact of a diode control bulb to bring to "weight".
  4. If the bulb flashed, means, valve power supply as it should be. Therefore, it is necessary to check the valve:
  5. To connect an ohmmeter and to check resistance on plug contacts of the valve.
  6. If the valve is serviceable, the indicator of resistance should make 2 — 10 Ohm.
  7. If the standard size is not reached, to replace the valve.
  8. At the correct resistance the cause of defect should be looked for in a rupture of conducting or defect of the control unit system of injection of Digifant.
  9. For check of regulation the operating current is measured. For this purpose the workshop applies the device to poll of memory of the store of malfunctions by V. A. G 1551, measurement by make-shifts is not meaningful.