【Fault description】
    Idle instability and often flameout. Other conditions without exception, the computer did not save the fault code.
    【Inspection process】
    Check the throttle position sensor, the idle contact contact is good. Remove the idle motor, check the opening and closing of the action, stretching smooth, no jamming phenomenon. Check the spark plug, cleaning with the engine does not disassemble the washing machine. After that, the fault has not been ruled out. Measured with a fuel gauge fuel pressure of 252kPa, belonging to the normal range. Check the fuel injectors, all the conditions of fuel injection are normal. Finally, it is suspected that the exhaust gas recirculation system may be defective. Unplug the vacuum control solenoid valve to the exhaust gas recirculation valve between the vacuum tube, the phenomenon immediately disappeared. With your fingers to block the electronic control vacuum switch solenoid valve vacuum tube and found that there is still a vacuum when idle, thus judging the electronic control vacuum switch solenoid valve is faulty.
    【Fault Analysis】
    The electric control exhaust gas recirculation system is composed of an exhaust vacuum control valve, an electric control vacuum switch solenoid valve and an exhaust gas recirculation valve, wherein the electronic control vacuum switch solenoid valve is responsible for controlling the exhaust gas vacuum regulating valve and the exhaust gas recirculation valve vacuum passage The At idle and full load conditions, the electronic control vacuum switch solenoid valve closed, cut off the exhaust vacuum control valve and exhaust gas between the vacuum channel, so that the exhaust gas recirculation valve is also closed to stop the exhaust gas recirculation. The car electric control vacuum switch solenoid valve closed lax, resulting in exhaust gas recirculation can not stop. Because the full load and other conditions of the large number of fresh air mixture, by the impact of relatively small exhaust, the engine power drop less difficult to detect. While the idle air when the small number of mixed air, resulting in the engine idling instability and often turn off. The vehicle is equipped with a position sensor on its exhaust gas recirculation valve to detect abnormalities in the operation of the exhaust gas recirculation valve, to cause the fault light to light up and to store the fault code. From the truth, the occurrence of this failure, the computer should save the fault code. However, due to electronic control vacuum switch solenoid valve leakage is small, the position sensor is not detected, resulting in the computer does not save the fault code.
    【Maintenance】
    Replace the electronic control vacuum switch solenoid valve, troubleshooting.