BMW 5 Series E39

since 1996-2001 release

Repair and operation of the car

+ Introduction
+ Maintenance instruction
+ Current leaving and service
+ Engine
+ Cooling systems, heating
+ Power supply system and release
- Engine electric equipment
   - System of ignition
      Security measures during the work with system of ignition
      Removal and installation of the coil of ignition
      Removal and installation of the sensor of a detonation
      Check and replacement of the sensor of impulses
      Removal and installation of the plug of a spark plug
      Removal and installation of the DME control unit
      Spark plugs
   + System of preheat of the diesel engine
   + Systems of a charge and start
+ Manual transmission
+ Automatic transmission
+ Coupling and power shafts
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment
+ Schemes of electric equipment
+ System of onboard diagnostics


System of ignition

The system of ignition generates sparks which ignite fuel mix. For ensuring necessary energy of ignition the coil of ignition will transform tension of the rechargeable battery of 12 V to tension of 30 000 Century.

The diesel engine has no system of ignition. Here thanks to high extent of compression air heats up to temperature providing spontaneous ignition of fuel at its injection.

Petrol engines of the BMW cars are equipped with direct adjustable system of ignition. Control of ignition is exercised of an electronic control unit the engine. The system has no ordinary distributor of ignition. Distribution of ignition on cylinders is run by the electronic block which does not have mobile parts. Ignition tension moves six independent coils of ignition located over candles here. Synchronization of ignition is carried out by system by means of the signals developed by the pulse sensor. The sensor is ahead at the block of cylinders. The sensor works depending on engine speed.
For definition of the necessary moment of ignition the control unit uses the corresponding characteristics of ignition. It allows system of ignition to adapt to various service conditions.

The moment of ignition depends also on the data obtained from the detonation sensor. As fuel consumption is minimum at higher extent of compression, in modern engines extent of compression is established by maximum. On the other hand high extent of compression can lead to uncontrollable process of combustion that is shown in an engine detonation. Long influence of a detonation leads to damage of the engine. For an exception of this phenomenon the detonation sensor registering emergence of a detonation and transmitting a signal of it to the control unit which in turn displaces the ignition moment in the direction of later is installed. The BMW engine has two sensors of a detonation located in the block of cylinders. One sensor registers a detonation in cylinders 1-2-3, another in cylinders 4-5-6. Existence of the sensor of a detonation allows to apply less detonatsionnostoyky fuel (AI-91 gasoline). It must be kept in mind, however, that it leads to deceleration of power of the engine. Use of AI-98 gasoline leads to increase of engine capacity.

All elements of system of ignition are coordinated with each other and provide the optimum moment of ignition. Adjustment of the moment of ignition is impossible.

During the work with electronic system of ignition it is necessary to observe the appropriate measures of safety for an exception of traumatizing people or damage of system.