Models 260 and 300 with EZL ignition system
The EZL ignition system includes spark plugs, high voltage wires, ignition distributor, ignition coil and ECU electronic control unit along with sensors, actuators and electrical wires. The principle of operation of the ignition system is the same regardless of the location of the components and elements of the ignition system, depending on the model of the car.
The ignition control unit supplies voltage to the primary winding of the ignition coil. At the required moment, the control unit disconnects the voltage from the ignition coil, which leads to a drop in the magnetic field in the primary winding and induces a high voltage in the secondary winding of the ignition coil. High-voltage voltage at a certain moment from the ignition coil through the ignition distributor and high-voltage wires is supplied to a specific spark plug. When high voltage is applied to the spark plug, a spark forms between the electrodes of the spark plug, which ignites the fuel-air mixture in the engine cylinder. The determination of the moment of ignition of the fuel-air mixture is carried out by an electronic control device.
Determination of the ignition timing and its constant adjustment is carried out by an electronic control device (ECU) based on information about engine speed, crankshaft position and vacuum in the intake manifold obtained from sensors installed on the engine. Also, when determining the ignition timing, information about the position of the throttle is taken into account (removed from the throttle limit switch), the temperature of the air entering the engine and the temperature of the coolant.
Based on information from the camshaft sensor, the ECU determines which cylinder is currently igniting the fuel. The sensor installed in the cylinder head induces a signal when a protrusion passes near it on the end of the camshaft sprocket that controls the intake valves. As a result, the ECU controls the ignition timing individually for each cylinder, which in turn allows you to control the detonation in the cylinders.
On ignition systems with knock control, the knock sensor is mounted on the cylinder block. The knock sensor detects pre-ignition before detonation is manifested as piston pin clatter. When detonation occurs, the ECU reduces the ignition timing in that cylinder. Then, by gradually increasing the ignition timing in this cylinder, the ECU restores its original value until a new detonation appears.
Depending on the type of fuel used, the initial ignition timing can be changed with a switch plug located in the engine compartment next to the ECU.
Models 280 and 320 - 24V with HFM engine management
The HFM engine management system is an autonomous system that simultaneously controls the ignition and fuel injection system.
The operation of the HFM system is similar to that of the EZL ignition system with the following differences.
The HFM ignition system does not have an ignition distributor. The ignition unit consists of three ignition coils. Each ignition coil consists of two separate high-voltage windings that deliver a spark to two cylinders at the same time. The ignition pulse is applied immediately to two spark plugs for each engine cylinder, one on the compression stroke and one on the exhaust stroke. The ignition spark on the exhaust stroke does not affect engine performance and is therefore wasted. The ECU uses inputs from various sensors to calculate the required ignition timing and ignition coil storage time.
To identify faults in the engine management system, it is necessary to use special electronic measuring instruments, and this work must be done at a service station.