A 2002 hatchback POLO1.4 sedan, engine model BCC, equipped with manual transmission, mileage of 100,000 km. As a result of the accident, the front of the car suffered heavy losses, but after several repair shop repair, the vehicle can not start. According to the user, the car has replaced the engine control unit and a number of sensors, and the cylinder head, transmission crack was welded repair.
    After the car, the maintenance staff first carried out a routine inspection of the vehicle and found that many of the engine compartment to the wrong direction, the other side did not find abnormal. Connect the fault diagnosis machine V. A. G1552 to detect the car, found the fault meaning "from the airbag control unit data bus did not get the signal" fault code. After inspection, the steering wheel is not equipped with airbags, that this failure is not directly linked with the engine does not start. At this point start the engine, there is no sign of any start. As the engine uses a stand-alone ignition system, the pen-type ignition coil removed plug the spark plug and make it off the ground, check the high pressure fire, found the spark is weak; pull out the injector test spray, oil spray. After measuring the cylinder pressure, only 750kPa, respectively, in the spark plug hole injection of some oil, cylinder pressure rose to 1050kPa. And then start the engine, only to hear the intake pipe "flapping" the sound of fire, the exhaust pipe collapse, collapse of the sound of burning, according to experience to determine, like the ignition timing caused by the ignition disorder symptoms.
    At this time calmly think about it, the car's fault symptoms as if the general EFI car crankshaft position sensor failure, can not transmit the signal, making the engine control unit can not accurately confirm the crankshaft first cylinder top dead center position and engine speed failure The The control unit J448 will calculate the engine speed based on the signal provided by the camshaft position G40 sensor, although the engine control unit J448 will enter the emergency operating state even if the crankshaft position sensor is unplugged. Determine the camshaft position, start the engine. At this time, it was proposed to pull out the crankshaft position sensor test, unplug the sensor plug, the engine started. But why plug in the crankshaft position sensor can not start it? It seems only to remove the transmission to find the answer. After removing the transmission, you can find the engine speed G28 sensor trigger wheel integrated in the crankshaft after the sealing flange, G28 sensor with hex bolts fixed on the flange, but now the screw hole with hexagonal tool head, Just flat with the bolt plane, has been unable to disassemble, can be determined to be caused by artificial demolition.