Audi 80/Avant (B4)

since 1991-1995 release

Repair and operation of the car

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
- System of injection
   + 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 the 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 electrical system
+ System of ignition
+ 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 gasoline outflow back in a fuel tank.

On the right: the provision of a butterfly valve is reported to the control unit of 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 the 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 the idling mode pressure of supply of fuel has to make about 2,5 bars, at the vacuum hose removed from pressure regulator it has to raise to 3 bars.

Check of a potentiometer of a butterfly valve


  1. To disconnect the plug 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 has to change evenly. At the left: vpryskny nozzles (shooter) are located on right in the direction of the movement 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 plug (1) is removed from a vpryskny nozzle (2). With the LED voltmeter it is possible to check, whether as it should be power supply of vpryskny nozzles.

For electric checks it will be required to you light-emitting diode volmetr.


  1. Check of power supply: one by one to remove plugs on vpryskny nozzles.
  2. To connect the voltmeter to contacts of the removed plug.
  3. The assistant has to start the engine.
  4. Light-emitting diodes have to flicker, otherwise there is a defect in conducting to nozzles or the control unit is faulty.
  5. Check of nozzles: to remove all plugs on vpryskny nozzles.
  6. To connect an ohmmeter to both plug contacts of the first vpryskny nozzle.
  7. Standard indicator: 15 — 20 Ohms.
  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 have to remain put on, and toplivoprovodny hoses connected.
  12. At the left in a branch pipe of the cooling system to remove plugs of the starting valve and the sensor of temperature.
    To send vpryskny nozzles to four measuring capacities.
  13. Now the assistant has to scroll a starter within several seconds: all four nozzles have to have an identical vpryskny stream. In this case type of a stream as it should be.
  14. To remove the central plug 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 have to 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 the arriving air are represented.


  1. Sensor of temperature of inlet air: to separate the 4-contact plug from above on an air flowmeter.
  2. To connect an ohmmeter to both external shtekerny contacts.
  3. Sensor of temperature of cooling liquid: to disconnect the blue plug from the sensor in a bulk branch pipe of the cooling system.
  4. To connect an ohmmeter to plug contacts of the sensor.
  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 time of measurement within a curve.
  7. If this is so, so 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 plugs from all vpryskny nozzles.
  2. Power supply: to remove a wire tip on the starting valve.
  3. To connect to the plug the LED voltmeter with auxiliary conducting.
  4. To disconnect the plug from the sensor of temperature of cooling liquid.
  5. The assistant has to turn a starter the engine, thus the light-emitting diode has to flash on 1–4 villages.
  6. If it does not occur, so conducting is interrupted, or the control unit of system of injection of Digifant is faulty.
  7. Action check: plugs of nozzles remain still disconnected.
  8. To turn off the starting valve, tips of wires and a tube of a fuel-supply line remain connected.
  9. To disconnect the plug 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 has to 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 externally 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 measurement of the contents WITH so it is possible, it is necessary to visit a workshop. For the correct control the system of production of the fulfilled gases has to be serviceable, and a lambda probe has to receive power supply (whether as it should be safety locks?).


  1. To warm up the engine.
  2. To connect the device for measurement of the contents WITH.
  3. To start the engine and to leave to idle within at least 2 min.
  4. To increase rotation frequency to 2000 rpm.
  5. To write down the contents WITH.
  6. On the case of throttle knot to remove a vacuum hose of the regulator of pressure and to close a tubule a finger.
  7. The contents WITH for a short time has to raise, and then again fall up 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 plug (to the control unit) in turn to the positive and negative plug of the accumulator.
  10. If at this check the indicator WITH changes, so 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 the control unit is, so faulty.

Air flowmeter

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

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


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

Idling stabilization


  1. To include ignition – the valve has to make the 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 plug on the valve of stabilization of frequency of rotation of a shaft of the engine in the idling mode. With a diode control bulb to check existence of food in the plug on contact of a black-blue wire (at the included ignition). For this purpose to bring other contact of a diode control bulb to "weight".
  4. If the bulb flashed, so 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 has to make 2 — 10 Ohms.
  7. If 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 of system of injection of Digifant.
  9. For check of regulation the operating current is measured. For this purpose the workshop uses the device to poll of memory of the store of malfunctions of V. A. G 1551, measurement by make-shifts does not make sense.