A 2003 annual production of Changan Ford Carnival 1.6 sedan, mileage 80,000 km. In the normal driving suddenly turn off, then start the car can not start. This car is equipped with a multi-point sequential jet single overhead camshaft 4 cylinder ROCAM engine, 5 speed manual transmission.
    Vehicles into the factory, the first basic inspection. Oil, coolant and fuel and so on in the normal range, the starter can start normal operation, but that is not the car. Use the fault diagnosis instrument to retrieve the fault code, display system is normal. Taking into account the engine is running in the sudden failure, and no fault code storage, so there may be a fuel system failure. Connect the fuel pressure gauge, measuring the starting pressure of about 230kPa, in the normal range. Check the ignition system, the car is the two-cylinder at the same time ignition, that is, a cylinder and 4 cylinder at the same time ignition, 2 cylinder and 3 cylinder at the same time ignition, when a cylinder is located in the compression stroke on the ignition, while the other cylinder The top dead center of the exhaust stroke. Connecting a cylinder and 3-cylinder spark plug, respectively, to test fire, high voltage is very strong, was blue and white, indicating that the high voltage normal.
    After a night of parking, check the fault on the 2nd day. Maintenance personnel to remove the spark plug to measure the cylinder pressure, then found the 2-cylinder and 3-cylinder spark plug with a slight trace of gasoline, which should be a long time to start but can not be caused by the car. After the measurement, the cylinder pressure is above 800kPa, check the ignition timing mark in the normal position, which can basically eliminate the possibility of internal mechanical failure of the engine. Replace a group of spark plugs after starting the engine again, or not a car. Why can not the car with electricity? Troubleshooting can not be carried out at once.
    Maintenance personnel analysis, which the engine mainly by the crankshaft position sensor to control the ignition advance angle and fuel injection time, crankshaft position sensor target wheel with 60-2 tooth mode, less out of the two teeth in the interval of 120 ° position. Because the engine is fired at the same time, when the engine starts, the engine computer will control the 1-cylinder injector off several times, and through the camshaft position sensor to determine the location of a cylinder, this process is generally not more than 5s, the engine computer has been correct Of the cylinder position immediately after the open-loop control to closed-loop control, so the use of this control mode of the engine as long as the oil should be able to start with electricity.
    In the case of basic inspection did not find the problem, the maintenance staff had to use the BOSCH560 engine integrated tester on the engine for real-time data analysis. First unplug the 3-wire plug of the ignition coil and connect the probe head on the device to terminal 2 and terminal 3 of the 3-wire plug of the ignition coil to detect the output waveform of the engine computer to the ignition coil. Figure 1 shows the rectangular wave of the engine output at start-up. The general basis for judging whether the waveform is correct is to confirm the consistency of the scale, frequency and shape of the waveform. Also note whether the output signal has an interference wave The The distance between the first rectangular wave and the second rectangular wave in the signal waveform of the signal waveform is related to the rotational speed of the engine, so that the coincidence of the frequency can not be judged. But the observed amplitude is about 12V, the pulse width is basically the same, and no other interference clutter, it can be concluded that the crankshaft position sensor, engine computer and related lines for the ignition coil to provide the primary signal is normal.