market dynamics
Electric jet motorcycle crankshaft position sensor is broken what is the phenomenon?
Release date:2020.08.26

The detection of crankshaft position and the control of ignition coil energizing time are the most basic elements of engine ignition advance Angle. The role of crankshaft position sensor is to control engine ignition timing and confirm the signal source of crankshaft position.

The crankshaft position sensor is used to detect the upper stop signal of piston and the crankshaft Angle signal. It is also the signal source to measure the engine speed.

We all know that an engine starts firing at the end of a compression stroke, so how does an engine computer know when to fire and when to spray fuel? It is calculated by the crankshaft position sensor combined with signals from other auxiliary sensors. Based on the sensor signals collected, the ECU controls the timing of ignition and fuel injection to ensure that the engine is working properly.

The crankshaft position sensor is usually mounted on the side of the left crankcase cover and is mainly used to detect the crankshaft angular phase and engine speed. According to the principle of work, it can be divided into electromagnetic induction type, Hall type and photoelectric type, usually maintenance motorcycle is the most common electromagnetic induction type.

The crankshaft position sensor usually needs to work with the magneto rotor (also known as the flywheel, magnetic steel) to output the signal. There are usually 24 boss positions on the rotor of electrospray motorcycle magneto, evenly divided into the whole circumference, and only one boss is vacant in a certain position, so there are actually 23 bosses.

When the crankshaft position sensor moves to this vacant position, there is a significant flux signal change, which is picked up as the control signal.

If the crankshaft position sensor is broken, the crankshaft Angle can not be confirmed, the engine computer can not receive the signal of the crankshaft position sensor, in order to protect the engine will not ignite, do not spray oil to hit the car, resulting in the engine can not start. If the problem is minor, it may cause difficulty starting the engine or intermittent stalling during operation.

Then, how to determine the crankshaft position sensor is normal, or damaged?

One is the voltage measurement method. When starting the motor, a multimeter voltage file is used to measure the output voltage of the crankshaft position sensor. The normal signal voltage ranges from 0.3V to 1.2V (1.8V to 2.5V if normal operation is achieved). The "super test light" can also be used for perfect detection, there is a trigger signal, the super test light indicator will flash, and the higher the voltage, the brighter the indicator.

The other is resistance detection. The crankshaft position sensor coil was tested and measured using a multimeter resistance gauge. The normal resistance value ranged from 700 ohms to about 1000 ohms. Of course, this was only a general range, and the resistance value of different types of sensors varied.

The third is oscilloscope measurement method. The output waveform of the crankshaft position sensor can be measured when starting the motor. The waveform is as follows: every boss will produce a trigger signal, and there will be obvious signal jump at the missing gear position. The amplitude voltage is consistent with that measured by the first method.

The fourth is the measurement method of electronic spray detector. You can use [Fingertip Motorcycle] shop "MSC Bluetooth ELECTRONIC Jet Detector "to read the data stream. If the engine speed dial is always 0, it means that the output signal is abnormal.