What if BYD Qin doesn't idle when there is no power?

Byd Qin can find a diesel locomotive that does not idle when there is no power, and then connect the positive electrodes of the batteries of the two cars to the positive and negative electrodes respectively to start it, or replace BYD Qin with a new battery. If there is power loss or leakage, the battery needs to be replaced immediately, otherwise the vehicle will not start and the load in the vehicle will be dead.

A 2009 BYD F3 sedan with a mileage of about 67,000 km and equipped with Mitsubishi 4G 15S 1.5L engine. User feedback: The phenomenon of no idle speed suddenly appears when the car is driving.

When we picked up the car, we asked the user and knew that the car had been working normally until it broke down. On that day, the car was driving for about 20km, and suddenly there was no idling, but the engine could work normally under other working conditions.

In view of the failure, we made the following inspections:

1. Through trial operation, it is found that when the engine is idling, the engine will gradually turn off, and when the engine is working normally, the fault warning light will not light up, indicating that the engine electronic control system may be normal.

2. Connect the fault diagnosis instrument KT600, and read the fault code with OBD-II diagnostic plug. The result shows that there is no fault code.

1), indicating that the engine electronic control system works normally.

3. In the parking state, open the engine cover and gradually add and subtract the accelerator pedal after starting the engine, so that the engine can switch back and forth between light load and heavy load. Observe the working state of the engine, and the engine works smoothly without jitter and abnormal noise. When the accelerator pedal is released, the engine will gradually shut down again.

We know that BYD F3 car uses a bypass-air-passage idle actuator (as shown in Figure 2), and the engine idle speed is controlled by the engine ECU controlling the air volume in the idle passage through the idle valve. Through the above inspection and analysis, it is concluded that the idle air passage may be closed when the engine is idling, and no air flows through it, which can not provide the air needed for normal idle operation of the engine, resulting in engine flameout. When the engine works between light load and heavy load, the air required by the engine is mainly supplied by the main air port, and the amount of air flowing through the main air port is controlled by the throttle opening controlled by the accelerator pedal through the cable, so the engine can work normally except for idle working conditions.

Troubleshooting: Through vehicle inspection and fault analysis, we preliminarily judge that the fault may be that the engine idle valve is completely stuck, and the required air volume cannot be obtained when the engine is idle, resulting in automatic flameout when the engine is idle. Through communication with users, we know that the throttle valve has never been cleaned after purchase. In order to verify our judgment, the throttle body was disassembled, and it was found that the carbon deposition in the throttle body was very serious, and the carbon deposition in the idle side airway was more serious. The throttle body was thoroughly cleaned with carburetor cleaning solution. After refitting the throttle body, it was found that the engine was completely working at idle speed, and the engine completely eliminated the idle speed fault.

Fault summary: The main reason for the above fault is that the user failed to clean the throttle body about 20,000 kilometers according to the automobile maintenance schedule, resulting in more and more carbon deposits on the throttle body and the idle passage, which eventually led to the engine being unable to idle. It can be seen that the normal maintenance of the car is very important. In strict accordance with the provisions of the automobile maintenance cycle table, we should regularly go to the automobile maintenance enterprises to carry out the maintenance of the corresponding projects, so as to keep the automobile in a normal state.

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