Table of contents: Hall sensor ↓ Engine speed sensor and ignition… ↓
Hall sensor
The switching on and off of current to the ignition coil mentioned in the section is provided (also passing through the control unit and the electronic switch) hall sensor, which is located in the ignition distributor on models with 4- and 5-cylinder engines, and at the rear of the left cylinder head on models with 6-cylinder engines. Its name is associated with the name of the Hall effect opener. The Hall sensor is located at the bottom of the distributor housing and consists of the following elements: a switch (trigger) with 4, 5 or 6 notches (depending on the number of cylinders), permanent magnet and the Hall integrated circuit located opposite it. All together it functions approximately like a photo relay, the only thing is that here magnetic waves act instead of light. If the contactor plate is in the magnetic field, then the Hall sensor passes the current to the control unit. If the plate leaves the gap between the Hall integrated circuit and the permanent magnet, then the power supply to the control unit does not flow. These are the impulses that control the ignition.
Hint: The recesses in the distributor contactor are positioned in such a way that the high-voltage current pulse, for example in a 4-cylinder engine, reaches the control unit 60° before TDC. During this time, the control unit calculates the optimum ignition timing based on engine speed information (by means of a sequence of high voltage current pulses) and engine loads (via the resistance readings of the air flow meter, throttle potentiometer or intake manifold pressure sensor).
Engine speed sensor and ignition timing sensor. Models with 6-cylinder engines
In addition to the Hall sensor, 6-cylinder engines are equipped with an engine speed/rotation sensor and an ignition timing sensor. Both are inductive sensors.
The speed sensor works as follows: the sensor contains a coil and a magnet. They are complemented by toothed bosses on the flywheel. Every time a tooth passes under the sensor, the magnetic field of the permanent magnet changes, and voltage is created in the coil. This small signal is sufficient for processing in the MPI/MPFI injection system control unit.
In order to record the exact position of the crankshaft, a steel pin was installed at one specific point on the flywheel. If it passes under the sensor, a voltage spike occurs, which the control unit uses to determine the position.