How to repair the phenomenon of cylinder missing when Shenyang Jinbei finds idling jitter?

Engine jitter during acceleration of Jinbei station wagon: A SY6480AB-EH Jinbei station wagon is difficult to start when it is hot; Easy to turn off when idling; Engine jitter during acceleration; When accelerating rapidly, the engine speed can't go up, but it is easy to stall. Troubleshooting: The car is equipped with an electronically controlled single-point injection engine. According to the analysis of the fault phenomenon, the reason of the above fault is that the air filter is seriously blocked; Insufficient fuel pressure: fuel nozzle is blocked; Ignition system failure; Sensor failure and control module failure, etc. There is no fault display device on the dashboard of the car, and there is no necessary maintenance information at present, so we can only start with oil and circuit inspection. First, four spark plugs were removed, and it was found that the spark plugs were black, carbon was deposited on the electrodes, and the gap between the electrodes was too large. Then, measure the resistance of each high-voltage line. Results All the resistances of high voltage lines were qualified (all less than15kΩ). The impression after inspection is that the ignition efficiency of the car is not good and the mixture is too thick. Then the throttle body was removed from the air inlet, and it was found that there was a layer of carbon deposit in its inner cavity. Clean the inside and outside of the throttle body with carburetor cleaner, and then remove the nozzle and idle motor on the throttle body for cleaning. Then check the vacuum output pipe (on the intake cavity) connected to the intake manifold pressure sensor, and find that the vacuum output pipe has been blocked by carbon deposit. After inspection, the cause of the failure is basically clear. Due to the blockage of the vacuum outlet pipe, the pressure sensor of the intake manifold cannot receive the vacuum change signal of the intake and output the corresponding electrical signal. The electronic control module can't receive the electrical signal output by the intake manifold pressure sensor, so it has to start the backup program to keep the engine running. In addition, the ignition system has also failed, resulting in a great decline in engine performance. Dredge the vacuum output pipe with a steel drill and clean it with carburetor cleaner. Connect the vacuum outlet pipe on the intake cavity with a new hose and the intake manifold pressure sensor, and install four new spark plugs on the engine. Then start the engine. At this time, the idle speed of the engine accelerates steadily, and all the faults are eliminated. Troubleshooting of Jetta King Idle Wagon ● Model: Jetta King (equipped with 4-cylinder 20-valve engine). ● Fault symptom: After the engine is started, the idle speed swings between 300- 1500 rpm. After shaking for several times, it stabilized at the normal value, but it felt basically normal during driving. ● Analysis and maintenance: The reasons for idling may include: abnormal electronic control system and air leakage in intake pipe. Check with Jacky 43 1ME electronic control system detector, and get the fault information of abnormal signal of air flowmeter. This kind of air flowmeter is a hot-wire air flowmeter. Check the wiring and connector, and the connection is normal. Its connector has four terminals, namely 12V power line, ground wire, 5V standard voltage and signal output terminal. The voltage signal measured from the signal output terminal is 0.03V, and it is 0.03V when starting the engine and accelerating and decelerating, that is, the output voltage signal has not changed, so it is determined that the air flowmeter has been damaged. From the conventional experience analysis, the damage of air flowmeter may cause the symptoms of poor acceleration or increased fuel consumption, but it has little effect on the symptoms of idle speed of traveling block. There may be air leakage in the air inlet, but no air leakage was found after inspection. Check the idle speed control motor and potentiometer, and no abnormality is found. In the driving state, it can be seen that the throttle is driven by the idle motor for feedback adjustment, and the idle speed rises normally when the air conditioner is turned on. Therefore, it is judged that the idle speed control system is normal. So is the fault caused by the wrong airflow signal? Therefore, the analog voltage value of idle speed is input into the computer from the signal output end of the flowmeter through the sensor analog tester. When the input voltage is about 1.3V, the idling deviation disappears. Restart the engine and there will be no idling. After replacing the air flow meter, troubleshoot. The Jetta GiX car died after being left overnight. Model: Jetta GiX car is faulty: the owner reports that the car sometimes runs out of power after being left overnight. Fault diagnosis: during the inspection after entering the factory, it was unexpectedly found that if the air conditioner switch was turned on, the blower could also operate when the car key was removed. Under normal circumstances, turning off the ignition switch and then turning on the air conditioner should not work. Through the circuit diagram analysis, the live wire of the blower comes from the contact unloading relay. Under normal circumstances, after the ignition switch is turned off, the contact unloading relay should not be closed. This fault can only indicate that the contact unloading relay is closed. Unplug the car key, then unplug the contact unloading relay, and the blower stops. But why does the unloading relay close the ignition switch contacts? The reason is further analyzed from the circuit diagram. The control end of the contact unloading relay is ignited from the ignition switch through a black and yellow wire and grounded through the central relay box, which is the controlled end. The live wire of the headlight switch lighting circuit also comes from the black and yellow wire, which is grounded through the ground wire of the headlight switch. When the ignition switch is turned on, the headlight switch lights up. Repair measures: The fault can only be an internal short circuit of the headlight switch, so that the normal line leading to the headlight switch is connected with the black and yellow line of the lighting circuit of the headlight switch. After the ignition switch is turned off, the control end of the contact unloading relay catches fire, which makes the relay attract. Troubleshooting after replacing car headlights switch.