Ignition System: Description and Operation

EZL Function Diagram:

PURPOSE
The Bosch EZL ignition system delivers a precisely timed, high energy spark to the combustion chamber to ensure efficient combustion, optimum performance, and strict emissions compliance. The high tension ignition system delivers sufficient energy to ignite the air/fuel mixture under all normal operating conditions.

COMPONENTS
The EZL computerized ignition system consists of the EZL control unit, ignition coil, high-tension distributor, ignition wires with suppression connectors, and spark plugs.

EZL Inputs and Outputs:

OPERATION
The ECU receives input signals from the ignition switch, crankshaft position sensor, reference resistor, intake manifold vacuum signal, coolant temperature sensor, air temperature sensor, throttle valve switch, and the CIS-E control unit. The ECU then processes these signals, calculates the appropriate dwell/ignition angle, and switches the ignition coil primary ground circuit.

The positive primary side of the coil is connected to the positive battery terminal via the ignition switch. During primary current-flow (coil saturation) the coil is connected to ground through the power output transistor of the EZL control unit (ECU).

Ignition Map:

The EZL control unit contains ignition "maps" for both manual and automatic transmission equipped vehicles. The resistance of the reference resistor determines which map is used. (1.3 kOhm, Manual; 2.4 kOhm, Automatic)