Mercedes W124

since 1985-1995 of release

Repair and car operation

W124 Mercedes
+ Governing bodies and control devices
+ 2. Maintenance (diesel engines)
+ 4. Repair of 6-cylinder petrol SOHC engines
+ 5. Repair of 6-cylinder petrol DOHC engines
+ 6. Repair of the diesel engine established in the car
+ 7. Major maintenance of engines
+ 10. System of injection of BOSCH CIS-E fuel (KE-JETRONIC)
+ 11. System of injection of BOSCH HFM fuel
+ 12. Fuel system of diesel engines
+ 13. Fuel system of diesel engines
+ 15. System of ignition of 4-cylinder petrol engines
- 16. System of ignition of four-cylinder petrol engines
   16.2. General information
   16.3. Check of system of ignition
   16.4. Ignition coil
   16.5. Distributor of ignition and distributor rotor
   16.6. Check and adjustment of a corner of an advancing of ignition
   16.7. Elements of a control system of ignition
+ 19. Mechanical transmission
+ 20. Automatic transmission

16.2. General information

Models 260 and 300 with system of ignition of EZL

The system of ignition of EZL includes spark plugs, high-voltage wires, the ignition distributor, the coil of ignition and the electronic control ECU device together with sensors, executive mechanisms and electricly ми wires. A principle of action of system of ignition identical irrespective of an arrangement of knots and elements of system of ignition depending on car model.

The control unit submits ignition tension on primary winding of the coil of ignition. During the demanded moment the control unit disconnects tension from the ignition coil that leads to falling of a magnetic field in primary winding and induces a high voltage in a secondary winding of the coil of ignition. High-voltage tension at some point from the ignition coil via the distributor of ignition and high-voltage wires moves to a certain spark plug. At receipt of a high voltage on a spark plug between electrodes of a spark plug the spark which sets fire to fuel - an air mix in the engine cylinder is formed. Definition of the moment of firing fuel - an air mix is carried out by the electronic control device.

Definition of a corner of an advancing of ignition and its continuous adjustment is carried out by the electronic control device (ECU) on the basis of information on engine turns, the provision of a cranked shaft and depression in the inlet collector, received from the sensors established on the engine. Also at definition of a corner of an advancing of ignition information on the provision of a butterfly valve (acts in film from the switch of extreme provisions of a butterfly valve), to the air temperature, arriving in the engine and temperature of cooling liquid is considered.

On the basis of information from the camshaft sensor the ECU block defines, in what of cylinders at the moment there is a fuel ignition. Established in a head of the block of cylinders the sensor induces a signal when passing ledge about it at an end face of an asterisk of the camshaft operating inlet valves. As a result of it the ECU block operates a corner of an advancing of ignition individually for each cylinder that in turn allows to supervise a detonation in cylinders.

On ignition systems with detonation control the sensor of a detonation is established on the block of cylinders. The sensor of a detonation defines premature ignition before the detonation will be shown in the form of knock of piston fingers. At detonation emergence the ECU block reduces a corner of an advancing of ignition in this cylinder. Then gradually increasing a corner of an advancing of ignition in this cylinder the ECU block restores its reference value before emergence of a new detonation.

Depending on applied type of fuel the initial corner of an advancing of ignition can be changed the switching cap placed in a motor compartment near the ECU block.

Models 280 and 320 - 24V with a control system of the HFM engine

The control system of the HFM engine is an independent system which at the same time operates ignition and system of injection of fuel.

Work of HFM system is similar to work of system of ignition of EZL with the following differences.

In system of ignition of HFM there is no ignition distributor. The block of ignition consists of three coils of ignition. Each coil of ignition consists of two separate high-voltage windings which submits a spark at the same time to two cylinders. The impulse of ignition moves at once on two spark plugs for each cylinder of the engine, one – on a compression step one – on an exhaust step. The ignition spark on a step of an exhaust does not influence operation of the engine and therefore it is spent for nothing. The ECU block uses entrances from various sensors to calculate demanded installation of a corner of an advancing of ignition and time of accumulation of energy on the ignition coil.

For detection of malfunctions of a control system by the engine use of special electronic measuring devices is necessary, and this work is necessary for making at service station.