Ignition System: Description and Operation

IGNITION SYSTEM
High voltage for the ignition spark is generated in the module containing three ignition coils. Each ignition coil supplies two spark plugs simultaneously with high tension to produce a good spark. Ignition coil 1 thus causes a spark to be produced simultaneously in cylinders 2 and 5, ignition coil 2 in cylinders 3 and 6, and ignition coil 3 in cylinders 1 and 4.

The control module and a reference signal from the crankshaft position sensor ensure that correct timing information is supplied to the right ignition coil. As will be realized, the system has no conventional distributor.

The firing order is 1-2-3-4-5-6.

Depending on engine temperature, idling speed varies between 680 and 800 rpm.

At idling speed the ignition timing normally varies between about 8° and 12°, depending on engine speed and temperature.

In conjunction with upshifts or downshifts on cars with automatic transmission, engine torque is limited by retarding the ignition to -10°, provided that it is already less than this.

Ignition timing is determined by the control module, mainly on the basis of the following information:
- Engine speed (Td)
- Engine load (Tq)
- Knocking (if occurring)

Ignition coil No. Spark generated in cylinders
1 5 and 2
2 3 and 6
3 1 and 4