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A Chevrolet sedan. User response: the engine suddenly flameout while driving, and the exhaust pipe is black smoke when it starts again, but the engine is out of the car. Failure inspection: after checking, it is found that the timing pulley of the crankshaft pulley has been released and the timing belt is broken. Remove the cylinder cover and check the valve. The valve works well. After replacing the crankshaft pulley and timing belt, it is still unable to start. It was found that there was no high pressure fire on the high voltage line. After replacing the ignition module, there was no fire, so the engine computer ECU was suspected to be in trouble. Remove the computer shield, emitting a burning smell, check the circuit board, found burning marks. Change to a new computer test machine, high voltage line has high pressure fire, but the fuel injector does not spray. Remove the oil supply pipe, turn on the ignition switch, and find out that the gasoline is running out. When the engine is started, the gasoline spouts out, indicating that the gasoline pump and the oil circuit are normal. The vehicle is equipped with an 1.6L single point electronic control fuel injection engine. The fuel injection amount of the injector is controlled and corrected by 4 devices, namely, the intake pressure sensor, the throttle position sensor, the water temperature sensor and the idle speed stepping motor. If the first 3 sensors fail, the engine fault lights will flash, and the car fault lights are normal, so the idle step motor will be replaced, but the fault will remain. After checking, the valve timing is correct and the cylinder pressure is normal. After careful analysis, it was found that the fuel injection volume was too high due to the incorrect fuel injector type. Troubleshooting: after the replacement of the corresponding type of fuel injector, start the engine test, exhaust pipe black smoke phenomenon disappeared, the operation is not extinguished, the car started freely, troubleshooting. Fault analysis: the injector is actually a solenoid valve whose function is jet and atomized gasoline. The fuel injection, opening time and opening time are controlled by the electronic control unit according to the working state of the engine. Different engines are discharged, the computer, the injector and the injection pressure are not the same, and the type is not used in the wrong type. The injector will fail. When the vehicle was repaired at a roadside repair shop, it mistakenly installed a larger fuel injector, resulting in excessive fuel injection, resulting in excessive exhaust gas mixture and black smoke. In the maintenance of electronic control car, the difficulty is to find out the fault, and most of the elimination methods can be replaced, but the replacement must guarantee the same type, the same specifications, the same technical parameters, and the best also for the same manufacturer. Otherwise, new failures will occur.