General information about the ignition system (Peugeot 306)

Depending on the engine type, year of manufacture, etc., either an ignition distributor or an ignition coil with four connectors may be installed instead of a distributor. The sole function of this element, considered as a "voltage distributor", is to distribute high voltage to the spark plugs in accordance with the firing sequence. This is achieved by a dual, four-port ignition coil mounted on the flywheel side of the cylinder head, where the distributor would normally be located.

The primary ignition voltage is supplied by a control unit that is common to the ignition system and the fuel injection system. Primary voltage is supplied alternately to both parts of the ignition coil.

A four-output ignition coil mounted at the end of the cylinder head is used in the same way. It converts low voltage into secondary high voltage for the spark plugs. For every revolution of the engine, two sparks are produced, one at the end of the compression stroke and one at the end of the exhaust stroke. The latter is of course not used. Cylinders No. 1 and No. 4 form one pair, and cylinders No. 2 and No. 3 form another pair.

The ignition timing is adjusted according to the programmed parameter field and is adjusted depending on the engine speed and load. The current position of the crankshaft is determined by a sensor near the flywheel. Other factors that determine ignition timing are throttle position, coolant temperature, and absolute pressure.

The flywheel has a ring gear around its circumference that is missing two teeth at an angle of 180°, so that the dead center sensor accurately determines the moment of passing the top and bottom dead centers and transmits a signal to the control unit. Figure 174 shows the flywheel with the sensor on the right side.



The ignition coil simply screws on and off.



Thus, the ignition system installed on most engines consists of the following elements:

• The sensor is installed in the flywheel housing. This sensor sends a signal to the control unit that corresponds to the required moment of spark formation.
• An electronic control unit that also operates in the fuel injection system.
• Ignition system control unit.
• Ignition coil or ignition distributor.
• On 16-valve engines, a position sensor is installed on the cylinder head. It is tuned to a specific camshaft cam for the intake valves and determines the top dead center position of the first cylinder (once per working cycle, that is, every two revolutions).

The ignition system determines the ignition timing in the cylinders according to the data stored in the memory, which in turn is compared with the data coming from the sensor at the flywheel (engine speed and current flywheel position), air flow meter (engine load), sensor in the air flow meter (air temperature) and a sensor in the cylinder head (coolant temperature). The throttle switch provides information about the throttle position during engine starting, idle, full load and engine braking. The spark generation signal is transmitted from the ignition/fuel injection system control unit via the ignition switch to the ignition coil control.



On a 16-valve engine, the distributor, driven by the camshaft, distributes high voltage to the spark plugs in the firing sequence. On this engine, both ignition modules are electrically connected to the control unit. Both modules are connected to four coils (one module for two ignition coils). Ignition coils are mounted directly on the spark plugs instead of the conventional spark plug caps. Therefore, there are no high-voltage spark plug wires.

When working with wires or connectors of the ignition system and the associated fuel injection system, it is necessary to turn off the ignition. This will prevent possible short circuit.

Information copied from the resource (www.PEUGEOTBOOK.ru)