Causes and solutions of engine idling vibration and jitter
With the increase in vehicle usage time and mileage, the problems of large and small cars have gradually appeared, such as idling jitter, acceleration jitter, hot car jitter and other issues are more common. So, what is going on with car jitter, besides the spark plug, what other reasons might it cause?
Jitter caused by engine mechanical components
The engine will continue to wear during operation, and the gap between the inner wall of the cylinder and the piston will increase, but the degree of wear of each cylinder is not necessarily the same. In the cold start state, the oil lubrication effect is poor, and the cylinder and piston The gap may leak a part of the high-temperature gas, and at the same time cause the cylinder to be unstable, the power output is also reduced to a certain extent, and the cost of inspection and maintenance is also relatively high.
Water temperature sensor is abnormal
Whether the engine is running well or not is usually judged by the water temperature sensor. If the sensor’s information is conveyed incorrectly (usually manifested as a large difference between the information conveyed temperature and the real outside temperature), the engine’s injector will cause abnormal fuel injection and jitter problems. It is inevitable.
Abnormal fuel supply system
Fuel pump: The function is to deliver high-pressure fuel to the fuel distribution pipe to ensure continuous fuel supply to the fuel injection nozzle. When the fuel pump fails, it will cause the oil pressure to fluctuate, causing the engine to run unevenly. Checking this problem mainly relies on the fuel pressure gauge. During the detection process, connect the fuel pressure gauge to the fuel distribution pipe, run the engine at idle speed and observe the pressure value at this time. The value change can be used to preliminarily judge whether the fuel supply system has a problem.
When the fuel injection pressure is determined, the fuel pressure will directly affect the amount of fuel injected, as well as the concentration of the mixed gas. The fuel tank also has a channel connected to the activated carbon canister to absorb fuel vapor. Through the control of the solenoid valve, sending fuel vapor into the gas pipeline will also affect the concentration of the mixture.
Fuel injector: As the number of uses increases, fuel injectors may become blocked or leaked. Maintaining good driving habits can reduce carbon deposits. When there is a problem with the injector of a certain cylinder, the output of each cylinder will be inconsistent, resulting in jitter. The fuel injection nozzle should be kept clean, and if necessary, it can be cleaned or replaced regularly to ensure a good atomization state during fuel injection. To judge the quality of fuel injectors, professional maintenance personnel are required to draw conclusions through the test bench. The usual method is to "cut off the fuel".
Abnormal ignition system
Ignition coil: Provide energy for the spark plug to generate sparks. If there is a problem with the ignition coil, it will directly affect the quality of the ignition, resulting in a large amount of carbon deposits, which will be more serious under high-speed working conditions. The ECU at this location monitors the working status of the ignition system through a knock sensor.
Professional maintenance personnel can use the ECU to determine the specific location of the abnormality. In operation, when installing the ignition coil, pay attention to its sealing state, and the air under the coil must be drained clean, otherwise the expansion of the gas after heating will cause the ignition coil to pop out, which will cause the engine to shake.
Spark plug: When the vehicle is cold-started, due to insufficient internal temperature, the lubrication effect of the oil is limited, and the resistance will be relatively large. It needs more fuel injection to ensure the power requirements. Therefore, the ignition gap of the spark plug is very important. The larger the gap, the smaller the energy.
Because the mixed gas atomization effect is not good at low temperature, the energy required to start the engine ignition is high. When the engine is working for a long time, the ignition gap of the spark plug will gradually increase, but the ECU at this position cannot detect the problem. Maintain the previous working state, so that the output of a certain cylinder will be reduced, and the engine will shake.