Audi 80/Avant (B4)
since 1991-1995 of release
Repair and car operation
+ Technical specification
+ System of production of the fulfilled gases
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and airintaking channels
+ injection System
+ 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
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
Sensor of detonation combustion
Elements of a high voltage
Replacement of spark plugs
Check of the moment of ignition
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
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The system of ignition provides the correct passing of process of combustion in the engine thanks to purposefully "shot" igniting sparks. And everything occurs precisely because at average 3000 rpm of the engine each cylinder needs 25 sparks in a second. So the 4-cylinder engine will need 100 sparks in a second, 6000 in a minute, 360 000 at an o'clock and so on.
That ignition can
In order that in a spark plug in the combustion chamber the spark in general could slip, between electrodes of a spark plug there should be a tension of at least 30 000 Century. The storage battery gives, however, only 12 In tension. Thus, tension of the accumulator needs to be raised repeatedly. Duration of flash not the tenth, and not the 100-th, but thousand fractions of a second. It is necessary to it to work a little earlier or later, and efficiency of ignition, and thereby and engine capacity will be lowered.
When there is an ignition?
The spark should slip precisely at the right time. However to establish, when there will be this most necessary moment, not so simply.
VMT and ignition advancing
With increase of turns of the engine the igniting spark should jump over everything earlier as – we already mentioned it in the last section – the mix of fuel and air needs constantly same time to ignite. Only thus combustion occurs at the right time namely when the piston only begins movement down.
Combustion of a mix of fuel and air depends, however, and on its structure. If the pedal of an accelerator is squeezed out very little («partial loading»), ability of a mix in combustion chambers to ignition decreases: therefore it burns down more slowly and for this reason should ignite earlier.
In other situations it is necessary, that the moment of ignition moved towards late ignition. Ignition in that case occurs only when the piston passed for a long time VMT. Thus, ignition occurs practically in a release step that improves composition of exhaust gases, but worsens engine capacity. According to the aforesaid, late ignition is only correct, for example, at operation of the engine in a mode of compulsory idling (for example, at movement under a hill with the released pedal of an accelerator).