My car vibrates at idle speed, but it still vibrates when changing the spark plug and washing the accelerator. Turning on the headlights is even more shaking. It won't shake when driving. What happene

My car vibrates at idle speed, but it still vibrates when changing the spark plug and washing the accelerator. Turning on the headlights is even more shaking. It won't shake when driving. What happened?

When the engine is idling, the engine will shake, and the fault cannot be solved after replacing the spark plug to clean the throttle, and the headlights are more serious, which may lead to the fault (phenomenon). The comprehensive analysis is as follows (different models have different treatment methods):

A. air intake and exhaust

1. Idle speed control part: stepper motor and throttle body are dirty or leaking. Whether it has been equipped after cleaning (some models need to be equipped), check whether the cleaning process meets the operating specifications and whether the accessories are put back correctly. Some parts or systems are not "processed", so check each operation step in detail.

2. Leakage or blockage of the air intake system will lead to.

3. The sensors such as air pressure, temperature and throttle position are abnormal and the data is incorrect.

4. Check whether the EGR valve is normal.

B, oil pipeline

1. Abnormal fuel injector: It can be caused by its own quality failure, or by various defects such as foreign body blockage, poor sealing, and aging of aprons.

2. The electric fuel pump is abnormal or the fuel filter is blocked or transportation is blocked due to various reasons;

3. Whether the fuel pipeline is blocked and unobstructed, etc. Will lead to.

4. Abnormal rail pressure.

5, fuel quality will lead to. If there are too many impurities or too much water, the engine will work unsteadily and shake.

C, electrical

1, broken ignition coil, burnt out, poor conduction, etc.

2, ignition wire aging, leakage, resistance is wrong or abnormal.

3. The distributor is abnormal (see automobile emission standard);

4. Abnormal burner: it may be caused by exceeding the service life, incorrect resistance or calorific value, and unqualified quality. After replacement, carefully check whether the spark plug model is consistent with the original factory.

5. The matching step after partially cleaning the oil circuit was not performed.

6. The 6.ECU control module is faulty.

7. generators and batteries. Especially after the headlights are turned on, the jitter is more severe, indicating that the engine load increases and the power supply (quantity) has a certain impact. Focus on checking whether the power generation is enough to meet the standards; Whether the line from the generator to the battery is abnormal; Whether the battery is short-circuited or seriously insufficient (or does not store electricity), etc. Need to be checked.

8. Fuel rail pressure sensor. Whether it is normal.

9. Whether the values (data flow) of idle solenoid valve and stepping motor are correct.

D, heat dissipation

1, whether the temperature sensor is normal; The actual water temperature is detected by computer, and then compared with the normal value to see if it is consistent.

2. Whether there is leakage (overheating) or cylinder pulling in the heat dissipation part.

3. Whether the cooling fan is operating normally.

The above are common fault causes, and the possibility of other components or systems (due to too many models) is not ruled out, subject to the test results of real vehicles.