Troubleshooting: (1) Open the engine hood, find the self-diagnosis socket in the engine room, and short-circuit the holes E 1 and TE 1 on the diagnosis seat with wires; Turn on the ignition switch (but don't start the engine), observe the flashing of the "CheckEnginc" light on the instrument panel, and read the fault code. However, the "CheckEnginc" light flashes and the system is normal.

(2) Pull out the high-voltage lines of cylinders 1-6 in turn, and judge which cylinders don't work according to the change of engine operation. if

Unplug the high voltage line of a cylinder, and the engine operation has not changed, indicating that the cylinder is not working. Check the ignition, fuel injection and cylinder pressure of the cylinder. But after inspection, all cylinders are normal.

(3) Check the ignition timing with the ignition timing lamp, and find that the ignition timing is 10 at idle speed, which is normal. (4) Turn off the ignition switch, stop the engine, and remove the spark plugs in turn for inspection. It is found that the spark plug burns well, the electrode gap is 0.8mm and the insulation resistance is 10K? Above, all belong to the normal value, modified.

(5) Remove the air filter cover and reassemble it after the filter is clean and trouble-free.

(6) Remove the air inlet hose in front of the throttle valve and check whether the throttle valve is closed; Check the throttle line, which also meets the requirements; Unplug the connecting wire of the throttle position sensor, and measure the resistance value of the throttle position sensor without defects.

(7) Check the working condition of the idle speed control valve (ISC). When the ignition switch is turned off, you can hear the "click" sound from the ISC valve, indicating that the ISC valve has been closed.

Remove the terminal of ISC valve, unscrew the fixing screw of ISC valve, remove ISC valve, and measure S3 b 1 and S1; The resistance between B2 and S2 and S4 is (10-30? ), this is normal. Connect B 1 and B2 to the positive battery. S 1, S2, S3 and S4 are connected to the negative electrode in turn, the ISC valve is gradually opened, and B 1 and B2 are connected to the positive electrode of the battery. When S4, S3, S2 and S 1 are connected to the negative electrode in turn, the ISC valve gradually closes, indicating that the ISC valve works normally.

(8) Remove the negative battery, drain the engine cooling water, remove the drive belt, remove the power steering pump, remove the bypass water pipe, and finally remove the water temperature sensor. When checking the water temperature sensor, it is found that the water temperature sensing resistance is 16? , far greater than 3-0.2 at 20℃-80℃? . Therefore, it is considered that the resistance of the water temperature sensor deteriorates, which leads to the computer ECU misjudging that the temperature is low, resulting in air-fuel imbalance (too rich mixture) and poor idle speed. After replacing a new water temperature sensor that meets the requirements, install the negative terminal wire of the battery, start the engine and run normally at idle speed. The fault was finally eliminated.