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 Mono-Motronic
   + System of injection Digifant
   + System of injection KE-III-Jetronic
   - Systems of injection of MPI and MPFI
      Operating procedure
      Lambda regulation
      Malfunctions and independent diagnostics
      Independent repair
      Visual check
      Check of separate elements
      Removal of elements
      Hummock drive of "gas"
      Check of the mode of idling and analysis of exhaust gases
      List of malfunctions
+ 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


Lambda regulation

Catalytic converter can correctly work only if the coefficient of excess of air l is perhaps closer to 1 that corresponds to a ratio of fuel/air 14,7:1. In order that it was carried out in practice, systems of injection MPI/MPFI are supplied so-called a lambda regulation. At the same time the lambda probe measures amount of oxygen in exhaust gases – comparable size for composition of mix of fuel/air. If the indicator deviates from ideal, the control unit regulates composition of mix.

Regulation works in the range from l = 0,8 to l = 1,2, and fluctuations of this value are welcomed because only in this case catalytic converter copes with almost full transformation of harmful substances.

The lambda probe transmits a signal only after temperatures exceeding 350 °C. In order that this temperature range was reached as soon as possible, the probe is warmed electrically. Until the probe does not reach the working temperature, the system is lagged behind by unregulated and is guided on the set average coefficient.

As you already guessed: 6-cylinder Audi is supplied with two catalytic converters and also two a lambda probes.