Technical characteristics of the ignition system (Opel Kadett E)

The ignition system is fully electronic. It consists of a controller, a crankshaft speed and position sensor, an ignition distributor, an ignition coil and spark plugs. The ignition distributor only distributes high-voltage current to the spark plugs.

The microcomputer's read-only memory (ROM) contains 256 ignition advance angle values corresponding to 16 crankshaft speed values and 16 engine load values.

Based on the information received from the sensors, the microcomputer calculates the optimum ignition advance angle and compares it with the values stored in the ROM. If the calculated ignition advance angle coincides with the values entered in the ROM, the microcomputer uses this value. If the calculated ignition advance angle value is between any two consecutive values in the ROM, the intermediate memory device of the microcomputer determines the intermediate ignition advance angle value. The intermediate memory device can calculate three different intermediate ignition advance angle values. This ensures very high accuracy of ignition timing control.

Ignition coil

Brand and type: AC Delco 90 240 252.

Primary winding resistance at +20°C, Ohm: 0.300-0.652.

Resistance of secondary winding at +20°C, kOhm: 7.2-8.2.

Spark plugs

Brand and type: AC Delco CR 42 CXLS.

Thread of the screw-in part: M14x 1.25.

Gap between electrodes, mm: 0.7.

Octane correction shoe

The octane correction block is located on the left side of the engine compartment and ensures the adaptation of the controller's operation to regulate the ignition timing angle depending on the octane number of the gasoline used. When the engine is running on gasoline with an octane number of 95, the controller's output "15" is shorted to ground via the block through a 2202 Ohm resistor, and when using gasoline with an octane number of 98, this output is shorted to ground through a 750 Ohm resistor.

[Text copied from a web portal opelbook]