General Overview
EZK ignition system (with tachometer)Operation
The EZK ignition system is fitted only to 16-valve engines without turbocharger. This breakerless ignition system is equipped with a crankshaft sensor. It is controlled by a knock sensor, which provides the highest possible engine performance on any grade of fuel. This provides good fuel economy and cleaner exhaust gases.
When the ignition switch is in the start or drive position, ignition coil 320 with integrated amplifier and EZK control unit 176 will be energised (+15).
Control unit 176 receives ignition pulses via a three-core shielded cable from crankshaft sensor 345. The frequency of the pulses is proportional to the engine speed. The control unit then adjusts the timing on the basis of the following factors:
^ engine speed
^ engine load
^ any knocking tendencies
The ignition pulses supplied from terminal 16 of the control unit are amplified and adjusted in ignition coil 320 with integrated amplifier. A high-tension pulse is generated in the secondary winding each time a pulse breaks the primary circuit of the ignition coil. The high-tension pulse is then supplied to the corresponding spark plug (157) via distributor 6.
The ignition is set at 100 when the engine is started. This ignition setting is dependent on the speed of the engine, and adjustment starts at around 700 r/min. It is adjusted in accordance with the values stored in the control unit. The distributor has no centrifugal or vacuum advance mechanisms.) At idling speed (850 rpm), the ignition setting is about j40
Fuel system control unit 200 provides the ignition system with information on the engine load. Throttle angle transmitter 203 is closed (earthed) when the throttle is closed, i.e. when the engine is idling. When the load has exceeded the value stored in the control unit, the timing will be retarded by about 60 on all cylinders. The timing will return to normal in steps of around 10, in order to avoid heavy knocking on an increase in load.
The control unit receives information on knocking in any of the cylinders via knock sensor 178. The timing is then retarded only in the cylinder in which knocking was detected (in steps of around 30). This will continue until knocking has ceased or until the timing has been retarded by a total of about 130. The timing returns to normal in steps of 0.350.
EZK test tapping 145 is intended for special test equipment. Terminal 15 of the control unit delivers a pulse for each knock detected. (Positive voltage is supplied to the connector when the ignition switch is in the drive position.)
If a fault should occur in the control unit, a signal (earth) will be delivered from terminal 3, which will cause CHECK ENGINE warning lamp 47P to flash. This lamp can also be activated by the fuel injection system.)
Ignition pulses are supplied from terminal 17 of the control unit to timing service instrument socket 73, tachometer 110 and other systems that are dependent on ignition pulses.
Tachometer
Tachometer 110, located in combined instrument 47, is supplied across fuse 7 and 29-pole red connector H29-2 or 33-pole grey connector H33-2. The control pulses required for displaying the engine speed are supplied from EZK control unit 176.
Timing service instrument socket
Timing service instrument (TSI) socket 73 is intended for a special ignition service instrument and has the following terminals:
1. Positive supply direct from battery I
2. Earth
3. Solenoid (terminal 50) of starter motor 4
4. Positive supply from the ignition switch when the latter is in the start or drive position
5. Ignition pulses from EZK control unit 176
6. Not used
Fault-tracing hints
As a general rule, the connector to the control unit should always be disconnected when measurements are made on the ignition system cable harness. Use an ohmmeter, not a buzzer.
The ignition system will be energised when the ignition switch is in the drive position.
1. Check fuse 3, and check that terminal 15 of the ignition coil and terminal 4 of the timing service instrument socket 73 are live.
2. Check that terminal 6 of control unit 176 is live.
3. Tachometer: First check fuse 7 and check that the supply to it is live. Check that terminal 3 of the circuit board for tachometer 110 is live, and that ignition pulses are being supplied from control unit 176.
4. Check all connectors, cable harnesses and earth connections.