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Motor failure analysis
- Sep 11, 2018 -

1, the speed signal system failure

The engine speed and crankshaft position sensors detect their speed signals while the engine is running, provide crankshaft position signals, and serve as the main basis and basis for the control system to perform various controls. If the sensor or its line fails, the electronic control unit cannot receive the speed signal and the crankshaft position signal, and the fuel injection and ignition timing cannot be properly controlled. The injector does not operate and the spark plug does not jump. Check with the stethoscope and the timing light to confirm that the injector and spark plug are working.


When the above fault occurs, the general self-diagnosis system can display the fault code and comprehensively check the speed sensor, the 1 and 2 camshaft position sensors and their circuits. First disconnect the connectors of each sensor and check their resistance. If the resistance is not normal, they must be replaced. If it is normal, check whether the wiring and connectors of the ECU and each sensor are normal.


2, fuel pump and control circuit failure

If the fuel pump or control circuit fails, it will also cause the fuel supply system to have no fuel pressure. Even if the injector is working properly, the fuel cannot be injected normally. Check the method: connect the diagnostic plug-in terminals +B and FP with a short wire and turn on the ignition switch (do not start) to check the pressure in the oil inlet hose. If there is pressure in the hose and the oil can be heard, the fuel pump itself has no problem; otherwise, the fuel pump should be checked, and the resistance between terminals 4 and 5 can be measured with a multimeter. If it does not match the specifications, the fuel pump needs to be replaced. . If the fuel pump is working properly, its control circuitry should be checked, including fuses, EFI main relays, fuel pump relays, resistors, and wiring and connectors.


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