Audi A4

Since 1994 of release

Repair and car operation



Audi А4
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ Exhaust system
+ Cooling system
+ Fuel tank and the fuel pump
+ The air filter and channels всасывания
+ Injection system
+ Coupling
+ Transmission and the main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tyres
+ The electrotechnical equipment
- Ignition system
   That provides ignition
   When there is an ignition of a toplivno-air mix?
   Different systems of ignition
   So there is an ignition spark
   Executive office
   System brain
   The signals arriving in the block of management
   Detonation adjustment
   Be cautious in circulation with ignition
   Works on ignition system
   Search of malfunctions in ignition
   The ignition distributor
   High voltage knot
   Replacement of spark plugs
   Correct choice of spark plugs
   Check of the moment of ignition
+ Illumination
+ The alarm equipment
+ Tools and devices
+ Heating and ventilation
+ Body details
+ Salon
Search of malfunctions
Technical characteristics



When there is an ignition of a toplivno-air mix?

Drawing illustrates concept «Top dead point» and «Bottom a dead point». The space between them is working volume of the cylinder. On the contrary, between the higher position of the piston (2) and a bottom edge of a head of the block of cylinders (1) the combustion chamber is shown.


Basic element of system of ignition of the four-cylinder engine with working volume 1,6 l are the separate coil of ignition (1) and the terminal cascade (3) with a socket (2). Distribution of pressure of ignition on cylinders here carries out the ignition distributor.


Package of coils of ignition of the six-cylinder engine with the removed cover of the engine (static distribution of ignition). Figures on high voltage sockets explain, to what cylinder there is a wire.


In the engine of 1,8 l capacity of 92 kw the ignition coil on the cylinder 3 serves also the cylinder 1, and the ignition coil on the cylinder 4 – also the cylinder 2. Above on ignition coils the terminal cascade is established.


Ignition турбодвигателя 1,8 l capacity of 110 kw: each cylinder has an own coil of ignition (1–4).

The spark should slip in the combustion chamber in the fullness of time. Combustion of a toplivno-air mix occurs most effectively while it is compressed to the most minimum volume. This maximum compression is reached during that instant when the piston at end of a course of compression wishes to pass from progress to return movement of a working step. Before the piston passes to movement in the opposite direction, a share of an instant it is in the highest point of a trajectory of the movement. This point name «the top dead point» (ВМТ).

So, the ideal moment of ignition is that moment when the piston only begins the return movement. The compression maximum, and the piston can be wrung out with force to the engine block.

Despite it, would be wrong to establish the ignition moment precisely in the top dead point. As certain time (nearby 1/3000) before its ignition and development of a total pressure of combustion is required to a toplivno-air mix. Therefore the ignition moment is established for earlier term. We speak about «an ignition advancing». Therefore the starting shot for a spark sounds even during piston movement upwards, and pressure of combustion develops right after ВМТ.

The top dead point and ignition advancing

With increase in number of turns of the engine the ignition spark should slip all earlier since – as it was already told – the toplivno-air mix always needs the same time for ignition. Only so combustion process precisely in due time namely when the piston again only starts to move back is carried out. Combustion of a toplivno-air mix depends also on its structure. At slightly wrung out pedal of gas (at «partial loading») a mix in combustion chambers possesses the lowered ability to ignition, therefore it burns down more slowly and for this reason ignition too should work with the big advancing.

Installation of ignition with delay

In other situations it is necessary to shift the ignition moment in "a delay" direction. Ignition occurs when the piston passed for a long time already the top dead point. I.e. ignition is carried out almost on an exhaust step that improves structure of the fulfilled gases, but worsens capacity of the engine. Hence, later ignition can be correct when the engine works without loading in a mode качения the car (for example, downhill without gas).