Audi A4

since 1994 of release

Repair and car operation



A4 Audi
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ exhaust System
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and absorption channels
+ injection System
+ Coupling
+ Transmission and main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
+ Electrotechnical equipment
- Ignition system
   That provides ignition
   When there is an ignition of a fuel and air mix?
   Different systems of ignition
   So there is an ignition spark
   Executive body
   System brain
   The signals arriving in the control unit
   Detonation adjustment
   Be careful in the address with ignition
   Works on ignition system
   Search of malfunctions in ignition
   Ignition distributor
   Knot of a high voltage
   Replacement of spark plugs
   Right choice of spark plugs
   Check of the moment of ignition
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ body Details
+ Salon
Search of malfunctions
Technical characteristics





Detonation adjustment

The detonation ignition arising in case the moment of ignition it is established with too big advancing, harms to the engine. Its consequence are an overheat, damages of bearings and pistons.

On the other hand, the biggest exit of engine capacity happens when the moment of ignition is established with the maximum advancing, i.e. the engine rigidly works at detonation border. This border of a detonation is influenced by too numerous factors (quality of fuel, adjournment in combustion chambers and so forth) that it would be possible to define it precisely in advance.

Therefore at traditional installation of ignition it is necessary to have big «safety distance» or «a supervision post» which establishes – if there is a detonation combustion – detonation regulation.

Function of adjustment of a detonation

Combustion in cylinders is supervised by a so-called sensor of a detonation which is screwed at the left on the engine block. Two sensors are established in engines with working volume of 1,8 l (at the left on the block) and in six-cylinder engines (on the right and at the left above on the block).

The sensor of a detonation "feels", when combustion in cylinders instead of usual uniform fluctuations gives a picture of non-uniform fluctuations. The sensor transfers this information in the electronic control unit.

There is a following: at receipt of a signal «detonation combustion at the last ignition» cylinders following on turn continue to receive the moment of ignition calculated for them. But in that cylinder where the detonation was established, the moment of ignition moves approximately on 3 ° back. As it is noticed above, it occurs only in one cylinder. In others the moment of ignition calculated originally remains.

If detonation combustion in this cylinder remained, at the following working step the ignition moment again moves back on 3 °. It can be carried out at most to 15 ° (a reference point the nominal moment of ignition is).

If in the corresponding cylinder ignition occurs again normally, through short time the ignition moment again moves towards an advancing. It becomes approximately on 0,5 °, then the pause in some working steps while again there is no shift on 0,5 ° towards an advancing follows.

It proceeds until will reach originally planned moment of ignition or while the detonation sensor again will not give a signal about detonation combustion.

Detonation sensor

He listens, whether there is a detonation: the detonation sensor is in four-cylinder engines on the left side of the engine. In the six-cylinder engine is on one sensor of a detonation (shooter) on the right and at the left above under an inlet collector. Important: fixing bolts of a sensor of a detonation should be tightened precisely on 20 Nanometers, differently the sensor will not work.

The slice is inserted into this sensitive element «пьезокерамики», a material which we well know on gas pyezozazhigalka. Mechanical forces (stretching, pressure), operating on пьезокерамику, will be transformed by it to electric tension.

To make active sensor, enough non-uniform fluctuations which are made by detonation combustion.