Hall Sensor
The switching on and off of the current to the ignition coil mentioned in the section is provided (passing also through the control unit and the electronic switch) Hall sensor, which is located on models with 4- and 5-cylinder engines in the ignition distributor, and on models with 6-cylinder engines at the rear of the left cylinder head. Its name is associated with the name of the discoverer of the Hall effect. The Hall sensor is located at the bottom in the distributor housing and consists of the following elements: contactor (trigger) with 4, 5 or 6 grooves (depending on the number of cylinders), a permanent magnet and the Hall integrated circuit located opposite it. Everything together functions approximately like a photorelay, the only thing is that here, instead of light, magnetic waves act. If there is a contact plate in the magnetic field, then the Hall sensor passes current to the control unit. If the plate leaves the gap between the Hall IC and the permanent magnet, then no power is supplied to the control unit. These are the impulses that control the ignition.
Hint: The recesses in the distributor contactor are arranged in such a way that a high voltage current pulse, for example, with a 4-cylinder engine, enters the control unit 60°before TDC. During this time, the control unit calculates the optimum ignition timing based on the engine speed information (through a sequence of high voltage current pulses) and engine load (Via the resistance readings of the air mass meter, throttle valve potentiometer or intake manifold pressure sensor).
Engine speed sensor and ignition timing sensor. Models with 6-cylinder engines
In addition to the Hall sender, 6-cylinder engines are equipped with a speed/engine speed sender and an ignition timing sender. Both are inductive sensors.
The speed sensor works as follows: the sensor contains a coil and a magnet. They are complemented by toothed tides on the flywheel. Each time a tooth passes under the sensor, the magnetic field of the permanent magnet changes and a voltage is created in the coil. This small signal is sufficient for processing in the MPI/MPFI injection control unit.
In order to fix the exact position of the crankshaft, a steel pin was installed at one specific place on the flywheel. If it passes under the sensor, a voltage peak occurs, which the control unit uses to determine the position.
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