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
   Removal of a replaceable element of the air filter
   Purge of a replaceable element of the air filter
   Replacement of a replaceable element of the air filter
   Heating of inlet air
   Heating of an inlet collector
   Inlet collector with a changeable length of a path
+ System of injection
+ 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
+ Signaling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ Body elements
+ Search of malfunctions
+ Specifications





Heating of inlet air

The device of automatic heating of inlet air is on the entrance party of the case of the air filter. Its task – to maintain the necessary air temperature, soaked up by the engine.

It is important for the following reason: in cold weather gas mixture is formed better if inlet air moves warmed up. However at more high external temperatures the engine does not need supply of previously warmed up air: the same amount of warm air has bigger volume, than cold. As the engine can let in only certain amount of air, at the included preliminary heating of inlet air he receives less air and gas mixture becomes reenriched, the expense raises. So preliminary heating is necessary for uniform operation of the engine only at low temperatures.

Principle of work

Models with 4-cylinder engines: small engines have a vacuum regulation of preliminary heating of inlet air. Depression gathers at the engine behind a butterfly valve and affects the membrane mechanism of the vacuum regulator of an advancing of ignition which in turn opens the valve of heating of inlet air in an inlet branch pipe of the air filter.

In the vacuum pipeline conducting to the valve of the warmed-up air in the case of the air filter the temperature regulator interrupting free passing in this sleeve is switched in addition on if temperature of external air reached temperature from +35 to +45 °C (Mono-Motronic) or +20 to +30 °C (Digifant).

Malfunctions

  • Models with 5-and 6-cylinder engines: at these engines the valve of heating of inlet air is operated via the thermostat providing full access of warm air at –20 °C. At the increasing temperature the valve slowly is closed until it at +5 °C does not block completely access of warm air.
    If heating of inlet air does not function as has to, it is fraught with operation disturbances. In the winter:
  • Bad operation of the engine after start during the so-called period of warming up.
  • The engine works unevenly, with interruptions.
    In warm season:
  • Insufficient power, it is impossible to gather the maximum speed.
  • The increased fuel consumption.

Check of heating of inlet air

Models with 4-cylinder engines

 PERFORMANCE ORDER

  1. The temperature regulator is in the case of the air filter. Its tips of sleeves are available at the engine with system of injection Mono-Motronic from the lower party of the air filter.
  2. To disconnect a sleeve from a brass tip, or a tip with a mark.
  3. Mouth it is strong to involve air from a sleeve: the gate of hot air has to open or be closed with a sound.
  4. If it did not occur: to check the valve for ease of the course, a sleeve and the membrane mechanism of the vacuum regulator of an advancing of ignition on tightness.
  5. Then to check the temperature regulator. When checking air temperature has to be below +20 °C.
  6. To remove a sleeve tip to the air gate at the temperature regulator or at the valve of hot air.
  7. To remove a sleeve tip to the engine on the block of preparation of gas mixture or on the case of throttle knot.
  8. Mouth it is strong to involve air from a sleeve: the sleeve has to be "passable".
  9. The hair dryer to warm up the temperature regulator to more than 45 °C. Again it is strong to involve air from a sleeve: now it has to be closed.
  10. Otherwise to replace the temperature regulator.

Models with 5-and 6-cylinder engines

 PERFORMANCE ORDER

  1. To remove an air inlet sleeve behind a headlight cap
  2. To look in a sleeve branch pipe, if necessary to illuminate a small lamp.
  3. Depending on ambient temperature (see the previous section) the air gate has to close access of cold or hot air.

After removal of a sleeve of air supply at the 5-cylinder engine the valve (2) of preliminary heating of inlet air is visible. At once near it the thermoelement (1) setting it in motion is located. The position (3) shows the sleeve of the warmed-up air conducting to a final collector.

Sleva: on an illustration the case of the air filter removed and postponed in a motor compartment is shown. The membrane mechanism of the vacuum regulator of an advancing of ignition with the gate of hot air (2) is turned out from the filter case, the vacuum sleeve (shooter) is still connected:

1 – inlet branch pipe of cold air;
3 – sleeve of warm air.

On the right: the temperature regulator (2) heatings of inlet air is located at the 85 kW engine in a cover of the case of the air filter. The position (1) designates the vacuum sleeve suitable from the engine.








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