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
+ Coupling
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrosystem
- Ignition system
   Various systems of ignition
   Principle of work of ignition
   Executive body
   System "brain"
   Impulses for the control unit
   Regulation on a detonation
   Security measures at work with ignition system
   Repair of system of ignition
   Diagnostics of system of ignition
   Ignition distributor
   Sensor of detonation combustion
   Elements of a high voltage
   Replacement of spark plugs
   Spark plugs
   Check of the moment of ignition
+ Lighting
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
+ Specifications





Impulses for the control unit

The open distributor of ignition (on an example of the 4-cylinder engine):

1–Hall sensor;
2–zamykatel;
3–connecting tip of the sensor of the Hall.


The sensor of the Hall is located at the 6-cylinder engine far behind behind the left head of the block of cylinders:

1–case of the sensor of the Hall;
2–connecting tip.

Hall sensor

The inclusion mentioned in the last section and current switching off to the coil of ignition is provided (passing also through the control unit and the electronic switchboard – about it below) the sensor of the Hall which is located at models with 4-and 5-cylinder engines in the ignition distributor, and at models with 6-cylinder engines behind at the left head of the block of cylinders.

Its name has not something in common with big halls, etc., and is connected with a name of an opener of effect of the Hall used at operation of this sensor.

The sensor of the Hall is located below in the case of the distributor and consists of the following elements: a zamykatel (trigger) with 4, 5 or 6 dredging (depending on number of cylinders), a constant magnet and actually integrated scheme of the Hall located opposite to it. Everything together functions approximately as the photorelay, but here instead of light magnetic waves operate.

It becomes completely evident if we imagine an automatic door of the lift. If you rise in an aperture and will interrupt a ray of light, the door of the lift remains open. As soon as you departed and opened to light the road, the door mechanism obtains the order on closing.

Let's return to ignition system: if in a magnetic field there is a plate of a zamykatel, the sensor of the Hall passes a current to the control unit. If the plate leaves a gap between the integrated scheme of the Hall and a constant magnet, a food to the control unit does not arrive. It also is the impulses operating ignition.

 Help: dredging in a zamykatel of the distributor is located in such a manner that a high-tension current impulse, for example, at the 4-cylinder engine, gets to the control unit for 60 ° to VMT. During this time the control unit counts the optimum moment of ignition on the basis of information on number of turns of the engine (by means of sequence of impulses of a high-tension current) and loads of the engine (by means of indicators of resistance of a flowmeter of air, a potentiometer of a butterfly valve or the pressure sensor in an inlet collector).

Sensor of number of turns of the engine and sensor of the moment of ignition

Models with 6-cylinder engines

In addition to the Hall sensor 6-cylinder engines are equipped with the sensor of number of turns/frequency of rotation of the engine and the sensor of the moment of ignition. Both are so-called inductive sensors.

The sensor of frequency of rotation works as follows: in the sensor there is a coil and a magnet. They are supplemented by gear inflow on a flywheel behind on a cranked shaft. Each time when under the sensor passes a tooth, a magnetic field of a constant magnet changes, and in the coil tension is created. It is enough this small signal for processing in the control unit of systems of injection of MPI/MPFI. Information on number of turns of a cranked shaft thus arrives.

To fix the exact provision of a cranked shaft, on one certain place of a flywheel the steel pin was established. If it passes under the sensor, there is a peak of the tension, which control unit uses for situation definition.