Mercedes W124

since 1985-1995 of release

Repair and car operation



W124 Mercedes
+ Governing bodies and control devices
+ MAINTENANCE
+ 2. Maintenance (diesel engines)
+ ENGINE
+ 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
+ COOLING SYSTEM
+ FUEL SYSTEM
+ 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
+ SYSTEMS OF START, IGNITION
- 15. System of ignition of 4-cylinder petrol engines
   15.2. System of ignition of EZL
   15.3. System of ignition of TFZ
   15.4. Check of system of ignition
   15.5. Ignition coil
   15.6. Ignition distributor
   15.7. Distributor rotor
   15.8. Corner of an advancing of ignition
   15.9. Elements of a control system of ignition
+ 16. System of ignition of four-cylinder petrol engines
+ PRESTARTING HEATING
+ TRANSMISSION
+ 19. Mechanical transmission
+ 20. Automatic transmission
+ POWER SHAFTS
+ BRAKE SYSTEM
+ SUSPENSION BRACKET
+ BODY
+ ELECTRIC EQUIPMENT
+ CHECK OF MALFUNCTIONS






15.4. Check of system of ignition

GENERAL INFORMATION

Prevention

At work on ignition system it is necessary to be careful with the included ignition, as it is possible to receive blow a current from a high-voltage part of system of ignition. People with stimulators of warm activity are not recommended to check and make repair of system of ignition. Switch off ignition before disconnect niy or connection of any element of system of ignition or щупов the measuring device.


The main malfunctions of system of ignition are caused by easing or oxidation of contacts, or short circuit on mass of a high voltage because of pollution, humidity or damage of isolation of high-voltage wires. Before drawing a conclusion on malfunction of any element in ignition system, check a condition of wires or electric chains of system of ignition.

It is not recommended to check spark existence, holding a high-voltage wire at small distance from the engine as thus it is possible to receive blow an electric current or to put out of action the control unit ignition. Also it is not recommended to determine admissions of ignition by a method of consecutive removal of high-voltage wires from spark plugs. As a result of such check it is impossible to receive true result as the system of ignition established on later models, will find a gap in a chain and will disconnect a high-voltage wire.

The engine is not started

If at engine start the cranked shaft of the engine is not turned or turned very slowly, check a condition and a battery charging and a starter. Connect щупы the voltmeter to plugs of the accumulator and disconnect the central high-voltage wire from a cover of the distributor of ignition and connect it to weight. Include a starter no more than for 10 seconds, and measure tension on the accumulator. If at starter work tension becomes less, than 9,5 In, check an accumulator condition, a starter and charging system.

If at engine start the cranked shaft rotates with normal speed, using a stroboscope, check a high-voltage part of system of ignition. If at engine start the stroboscope blinks, means, the high voltage moves to spark plugs and it is necessary to check a condition of spark plugs. If the stroboscope does not blink, check the central high-voltage wire going from the coil of ignition to a cover of the distributor, coal contact and a distributor rotor.

If the spark is present, check a condition and operability of fuel system.

If the spark still did not appear, possibly, the block management of ignition is faulty and in this case it is necessary to address on service station of cars.

Ignition admissions

Unsystematic admissions of ignition can be caused by the weakened contacts or a rupture of a chain in a control system of ignition or in a chain of primary winding of the coil of ignition or damage of high-voltage wires.

Switch off ignition and check that contacts on electric sockets of system of ignition pure and without corrosion traces.

Check that the ignition coil, a cover of the distributor of ignition and high-voltage wires, pure and dry. Check a condition of electric wires of spark plugs. Then check a cover of the distributor of ignition, coal contact and a rotor of the distributor of ignition. Check of spark plugs can be made serial replacement of spark plugs by the new.

Constant admissions of ignition are caused, most likely, by defects in a cover of the distributor of ignition, the ignition coil, high-voltage wires or spark plugs. For check of giving of a high voltage to spark plugs it is possible to use a stroboscope.

Lack of tension only on one high-voltage wire testifies to damage of this wire or a cover of the distributor of ignition. If tension is present on all high-voltage wires, means, spark plugs are faulty.

At total absence of a high voltage check a secondary winding of the coil of ignition which can be damaged.

If at system of ignition there are malfunctions which it is impossible to eliminate independently, it is necessary to address on service station.