Ignition system — general description (Opel Vectra A)

1. The ignition system ignites the air/fuel mixture in each cylinder at the correct moment, depending on engine speed and load. A variety of ignition systems are available across the model range. From a standard electronic system with a breaker to a fully integrated engine management system that controls both the ignition system and the fuel injection system. Each system is described in more detail later in this Chapter.

2. The ignition system is powered by low voltage from the battery to the ignition coil where it is converted to high voltage. High voltage has enough power to create a spark between the spark plug electrodes under high compression. Low Voltage Circuit (or primary) consists of wiring from the battery to the ignition switch, wiring from the ignition switch to the primary winding of the coil and the power terminal on the electronic module, wiring from the primary winding of the coil to the control terminal on the electronic module. High voltage circuit (or secondary) consists of a high-voltage winding of the ignition coil, high-voltage wiring from the ignition coil to the distributor cover, distributor rotor, to the spark plugs and spark plugs.

3. The system functions in the following way. The current flowing through the low-voltage winding of the ignition coil generates a magnetic field around the secondary winding. When the engine rotates, the sensor generates an electrical pulse, which is amplified in the electronic module and used to turn off the low-voltage circuit.



4. The drop in magnetic field strength in the secondary winding generates high voltage, which is then supplied to the appropriate spark plug via the distributor cap and distributor rotor. The low-voltage circuit is automatically re-activated by the electronic module, the magnetic field begins to increase again and the cycle is repeated for the next spark plug. The ignition timing is adjusted automatically to ensure the exact moment of spark formation depending on engine speed and load.

HEI System

5. It includes a distributor with a breaker, an electronic switching/amplification module, an ignition coil and spark plugs.

6. The electrical impulse required to switch off the low-voltage circuit is generated by a magnetic trigger in the distributor. The trigger wheel rotates in a constant magnetic field. The magnitude of the magnetic field between the two poles (between the stator and gear projections) depends on the air gap between the two poles. When the air gap is minimal, the toothed wheel projection is located just before the stator projection, this is the moment of pulse generation. As the magnetic field between the stator and toothed wheel projections changes, a voltage is generated in the trigger winding mounted below the toothed wheel. This voltage is then amplified by the electronic module and used to switch off the low-voltage circuit. There is one trigger and stator projection for each cylinder.

7. Ignition advance is a function of the distributor and is adjusted mechanically and by vacuum. The mechanism of the mechanical regulator consists of two weights, which, when the engine speed increases, move away from the distributor shaft under the action of centrifugal force. Moving away from each other, the weights rotate the gear wheel relative to the distributor shaft and thus adjust the moment of formation of the ignition spark. The weights are held in position by two weak springs, and the correct operation of the ignition advance system largely depends on the tension of these springs.



8. The vacuum regulator consists of a diaphragm, one side of which is connected by a hose to a small hole in the carburetor, and the other side to the distributor. The vacuum in the intake manifold and carburetor, which varies depending on the engine speed and the position of the throttle valve, causes the diaphragm to move, which in turn moves the support plate and adjusts the ignition timing. The correct operation of the system depends largely on the stiffness of the spring in the diaphragm assembly.

MSTS-i System

9. This system has a "Hall effect" distributor (or crankshaft speed/position sensor on the X16 SZ model), intake manifold pressure sensor, oil temperature sensor, module, ignition coil and spark plugs.

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10. On 1.6 liter models, the electrical impulse to turn off the low-voltage circuit is generated by a sensor in the distributor. The trigger blade rotates in the gap between the permanent magnet and the sensor. The trigger blade has four slots, one for each cylinder. When one of the slots aligns with the sensor, a magnetic field is allowed to pass between the magnet and the sensor. The sensor senses the change in magnetic flux and sends a pulse to the MSTS-i module, which turns off the low-voltage circuit.

11. On 1.8 litre models, the electrical pulse to turn off the low voltage circuit is generated by the crankshaft speed/position sensor, which is activated by a special gear on the crankshaft. The gear has 35 equally spaced teeth, with the 36th tooth missing. This missing tooth is used by the sensor to determine the position of the crankshaft relative to TDC (top dead center) piston No.1.



12. Engine load information is sent to the MSTS-i module from a pressure sensor, which is connected to the carburetor by a vacuum tube. Additional information comes from the oil temperature sensor. The module selects the optimal ignition timing based on the information received from the sensors. The advance value can thus be constantly changed, depending on the engine operating mode.

Multec System with MSTS-i

13. The ignition system is fully electronic and has an Electronic Control Unit (ECU) installed in the driver's footwell. It includes: distributor (driven from the left end of the camshaft and containing a booster module) together with the fuel octane coding plug, spark plugs, high tension wires, ignition coil secondary winding and electrical wiring.

14. The ECU controls the ignition system and the fuel injection system, and is essentially the engine management system. For more information not covered here, see Sections 4B and 4C.

15. For the ignition system, the ECU receives information in the form of electrical pulses or signals from the distributor (about engine speed and crankshaft position), from the coolant temperature sensor (about engine temperature) and from the manifold pressure sensor (about engine load)In addition, the ECU unit receives information about the octane number of the fuel used from the coding plug (to adjust the ignition timing to the type of fuel used) and from the automatic transmission control unit (to soften gear shifts by reducing the ignition timing when shifting).



16. All these signals are compared by the ECU with the set values programmed into the memory. Based on this information, the ECU selects the ignition advance angle corresponding to these values and controls the high-voltage winding of the ignition coil via the amplifier module.

17. The system is so sensitive that at idle speed the ignition timing angle can constantly change; this must be remembered when checking the ignition timing.

18. The system installed on the C18 NZ models is similar to the one described above, except that the amplifier module is made as a separate unit. The ECU unit determines the engine speed and the position of the crankshaft using a sensor mounted on the right front end of the engine cylinder block. It is recorded by a disc with 58 teeth mounted on the crankshaft so that the gap formed by two missing teeth is a reference point indicating TDC to the ECU unit.

19. Note that this simplifies the operation of the distributor, which should simply supply a voltage pulse to the corresponding spark plug; and no more ignition timing adjustments are required

DIS system

20. On all X16 SZ engines, and on C20 XE engines (with two overhead camshafts) since 1993, the DIS module has been used instead of the distributor and ignition coil. On the X16 SZ engine, the DIS module is attached to the camshaft housing in the position normally occupied by the distributor. On the C20 XE engine, the camshaft phase sensor is attached to the cylinder head, located at the end of the exhaust camshaft, in the position normally occupied by the distributor. The DIS module is attached by a bracket to the cylinder head at the end of the intake camshaft.



21. The DIS module consists of two ignition coils and a control unit housed in a housing. Each ignition coil supplies high voltage to two spark plugs. One spark is generated in the cylinder with the piston on the compression stroke, and one spark is generated in the cylinder with the piston on the exhaust stroke. This means that one cylinder is supplied with an "extra spark" during each ignition cycle, but it has no harmful effect. This system has the advantage that there are no moving parts (therefore there is no wear and tear), and the system is largely maintenance-free.

Motronic M4.1 and M1.5 systems

22. This system controls both ignition and fuel injection.

23. The Motronic module receives information from the crankshaft speed/position sensor, the coolant temperature sensor located in the thermostat housing, the throttle position sensor, the air flow meter and, on models with a catalytic converter, the oxygen sensor located in the exhaust system (Section 4C).

24. The output signals from the module control the fuel pump, fuel injectors, idle speed and ignition circuit. Based on the input signals from various sensors, the module calculates the optimum ignition timing and fuel injector open time suitable for different engine modes. This system provides very precise engine control in all modes, improving fuel consumption and overall vehicle handling characteristics, and reducing harmful substances in the exhaust gases.

25. The components of the fuel injection system are described in more detail in Section 4B.

Motronic M2.5 and M2.8 systems

26. The system is similar to that described for models with one overhead camshaft, with the following differences.

27. Along with the crankshaft speed/position sensor, a distributor with a "Hall effect" is used (similar to that described in this Chapter for the MSTS-i system).

28. The system also has a separate ignition amplifier module that transmits amplified signals from the main system module to cause a high voltage pulse to the ignition coil. The module is mounted on the ignition coil bracket/backing plate.

29. Additionally, the Motronic module receives information from the knock sensor installed on the cylinder block, which is sensitive to knocking (or premature ignition), allowing the module to reduce the ignition timing, thus preventing engine damage.

Simtec 56.1 System

30. This system uses a large number of electronic components instead of mechanical parts such as sensors and actuators. They provide the system with more accurate data, based on which it is possible to more accurately control the engine operating modes.

31. The control unit is equipped with an electronic ignition control system called a microprocessor ignition system with inductive control, (or MSTS-i), And such a unit as a mechanical high-voltage distributor is no longer required. The unit is located behind the trim panel, on the right side in the footwell (in the door pillar).

32. The ignition coil is replaced by a dual coil, which is switched by signals from the control unit.

33. The sensor on the camshaft indicates critical positions when the inductive pulse sensor on the crankshaft is triggered. These positions are called TDC (Top Dead Center), crankshaft angle and engine speed. The signals are used by the control unit to calculate the ignition timing and fuel injection timing.



34. The air mass flow tape measure determines the mass of air entering the engine. The system uses this information to calculate the correct amount of fuel to inject into the engine.

35. The intake air temperature sensor (NTC) is installed in the intake air duct between the air filter and the air flow meter.

36. The system operates the carbon filter valve. Tank ventilation is controlled by Lambda control (or oxygen sensor) and is adjusted by the computer in the control unit.

37. There is also a detonation control system. It eliminates the need for octane adjustment, as this is done automatically by the control unit.