Ignition System: Description and Operation

EZL System Diagram:

The high tension ignition system must be able to deliver sufficient energy to ignite the air/fuel mixture under all conditions. If sufficient ignition energy is not available ignition does not occur and the resultant combustion miss produces reduced power and unacceptable tail pipe emissions. For this reason Mercedes Benz uses a simplified secondary ignition system consisting of the EZL control unit, ignition coil, high-tension distributor, ignition wires with suppression connectors, and spark plugs.

The primary side of the coil is connected with the positive battery terminal via the ignition switch. During the primary current-flow time (coil saturation) the coil is connected to ground through the power output transistor of the EZL control unit (ECU). The ECU receives input signals from the ignition switch, crankshaft position sensor, reference resistor, intake manifold vacuum signal, coolant temperature sensor, throttle valve switch, and the CIS-E control unit; processes these signals, and calculates the appropriate dwell/ignition angle, and simultaneously switches the ignition coil ground circuit.