SAAB WIS ONLINE

Ignition system (320a-d), E39

Ignition system (320a-d), E39

Location

The ignition coils, individually ex hangable, are fitted above the spark plugs on each cylinder, fastened with a screw.

Ignition coil with integrated power stage, cyl 1 (320a), E39

Ignition coil with integrated power stage, cyl 2 (320b), E39

Ignition coil with integrated power stage, cyl 3 (320c), E39

Ignition coil with integrated power stage, cyl 4 (320d), E39

Main task

The ignition system generates the ignition spark and and measures combustion quality. It comprises four inductive ignition coils, one for each cylinder, with an integrated final stage.

Type

Ignition system with inductive ignition coils and integrated final stage.

The ignition system receives four ignition trigger signals from the ECM control module, E39 (590) and returns two combustion signals.


Connection

Ignition system, cyl 1, 320a pin no Signal type Description
D Power supply, B+ Connected to fuse 2 in the petrol engine management system fuse box (727) via crimp connection J214.
A Ground Connected to grounding point G7 via crimp connection J225.
B Internal ground ECM Connected to ECM, pin 31(C), via crimp connection J213.
C Ignition trigger lead Connected to ECM, pin 30(C).


Ignition system, cyl 2, 320b pin no Signal type Description
D Power supply, B+ Connected to fuse 2 in the petrol engine management system fuse box (727) via crimp connection J214.
A Ground Connected to grounding point G7 via crimp connection J225.
B Internal ground ECM Connected to ECM, pin 31(C), via crimp connection J213.
C Ignition trigger lead Connected to ECM, pin 27(C).


Ignition system, cyl 3, 320c pin no Signal type Description
D Power supply, B+ Connected to fuse 2 in the petrol engine management system fuse box (727) via crimp connection J214.
A Ground Connected to grounding point G7 via crimp connection J225.
B Internal ground ECM Connected to ECM, pin 31(C), via crimp connection J213.
C Ignition trigger lead Connected to ECM, pin 29(C).


Ignition system, cyl 4, 320d pin no Signal type Description
D Power supply, B+ Connected to fuse 2 in the petrol engine management system fuse box (727) via crimp connection J214.
A Ground Connected to grounding point G7 via crimp connection J225.
B Internal ground ECM Connected to ECM, pin 31(C), via crimp connection J213.
C Ignition trigger lead Connected to ECM, pin 28(C).



Connections

ECM, pin 62(A), is connected to B+ at fuse 2 in the petrol engine management system fuse box (727) via crimp connection J214.

The ignition system is powered with B+ on the respective pins D via crimp connection J214 from fuse 2 in the petrol engine management system fuse box (727).

It is grounded through respective pin A to grounding point G7 via crimp connection J225

The ignition trigger leads from ECM are connected to respective pin C and the ECM ground for these is connected to ECM pin 31(C) via crimp connection J213.

Ignition

When the main relay in the petrol engine system fuse box (727) has operated, B+ is delivered to injector pins D. Once pin C on each ignition coil receives B+ from ECM, a power transistor integrated in the ignition coil will close the primary circuit.

The primary winding comprises relatively few turns of copper wire. A magnetic field now gradually forms in the ignition coil. When the spark is to fire, ECM applies B+ to pin C and high tension will now be induced across the secondary winding of the ignition coil.

The time during which ECM applies B+ to pin C to form the magnetic field in the ignition coils depends on battery voltage and engine speed. The voltage on the secondary side is much higher and it builds up until a spark jumps across the spark plug gap, which happens at approx 5-30 kV depending the conditions prevailing in the relevant cylinder. High pressure, which occurs when the engine is under load, requires a higher voltage than lighter running conditions.

The ignition coils can generate higher voltages, up to 40 kV.

Charging time, general

The charging time of the ignition coils depends on the system voltage and engine speed. The objective is to obtain a spark with the correct energy/high tension, irrespective of battery voltage and engine speed.

The charging time is in the region of 4 ms at 2000 rpm at normal system voltage.

Principle, voltage dependent

A lower battery voltage requires a longer charging time to obtain the same spark energy/high tension.

A higher battery voltage requires a shorter charging time, which avoids unnecessary ignition coil heating and reduces wear on the spark plug electrodes.

Principle, engine speed dependent

The charging time of the ignition coils is also engine speed dependent. This is to provide the correct energy/high tension to the spark. No more, which would stress the spark plug, and no less, which could cause misfiring.