Ignition (EZL/AKR)

EZL/AKR System Diagram:

EZL-AKR Control Unit Terminal Designations:

The EZL/AKR ignition control module contains a microcomputer, pressure sensor and the power output stage for control of the ignition coil. It is fitted to the left wheelhouse and is installed with heat conducting paste.

Ignition Control Unit Input-Output Chart:

The EZL/AKR control module receives information concerning:

^ Engine speed (crankshaft position sensor)
^ Engine load condition (intake manifold vacuum signal)
^ Engine temperature (coolant temperature sensor)
^ Shift preconditions (transmission overload protection switch)
^ Cylinder #1 position (camshaft position sensor)
^ Combustion knock (Anti-knock sensor)
^ Full load (throttle valve switch)
^ Selection of ignition map (reference resistor)

Ignition Map:

The EZL/AKR control module compares information from these inputs with ignition maps for typical load and speed ranges which are stored in the microcomputer. The optimal ignition timing for each operating condition is instantaneously determined from the stored maps and the power output stage switches the primary current of the ignition coil between terminals 16 and 31 of the control module. Furthermore, a TD (engine speed) reference signal is provided to the CIS-E 5 control module, tachometer, MAS control module, on-board diagnostic connector, and the diagnostic socket. To further increase operating reliability, a data exchange circuit has been added between the EZL/AKR control module and the CIS-E 5 control module. Information concerning the coolant temperature, intake air temperature and the intake manifold absolute pressure is continuously compared by the control module of each system.
During cranking and up to approx. 450 RPM, the ignition timing is controlled via the segment edges (fixed) of the flywheel. After approx. 460 RPM has been attained a transition from the fixed ignition timing to dynamic ignition timing (instantaneous, ignition map comparison) is made.
Various ignition characteristic curves are inhibited in the warm-up range depending on the coolant temperature in order to reach the normal operating temperature as rapidly as possible.
When a full load signal is received from the throttle valve switch the control module adapts a fixed full load ignition map characteristic. At temperatures above approx. 203°F the ignition will be retarded to counter any further rise in temperature.

ANTI-KNOCK CONTROL

The knock control system can, depending on the intensity of the knock, retard the ignition point for an individual cylinder between 2.5° and 5° of crankshaft angle per ignition cycle. The control module can continue to retard the timing up to a maximum of 13.5° in cases of extreme knock due to fuel condition, load, and excessively coolant temperatures.

MAXIMUM VEHICLE SPEED CONTROL

At a vehicle speed of approx. 155 mph the air/fuel mixture is leaned by the CIS-E 5 control module. At the same time the EZL/AKR control module retards the ignition timing to 15° before TDC. Should the vehicle speed remain over 155 mph, the camshaft is advanced, reducing engine torque further.

TRANSMISSION OVERLOAD PROTECTION

The transmission overload protection feature retards the ignition point for approx. 400 ms to 5° BTDC during the 1 - 2 and 2 - 3 upshifts at higher engine RPM, and the 3 - 2 full load kick-down shift. This measure provides reduced thermal stresses on the automatic transmission and also improves shift comfort. The ignition point is retarded when:

a. The engine speed is greater than 4000 rpm
b. A shift signal is sent by the transmission overload protection switch
c. Vacuum in the intake manifold is less than 9 in. Hg