What is the reason for engine shaking in cold weather?
The reason why the engine shakes in cold weather is that the engine water temperature is too low. In order to raise the engine temperature to the ideal operating temperature as quickly as possible, the fuel supply system will automatically enrich the mixture, which will intensify the engine operation, causing the engine to run unstable and causing large idling vibration.
Causes of abnormal engine jitter during cold start:
The most fundamental cause of jitter during cold start or [/k0/] gear waiting is poor combustion in the cylinder. If the combustion is not good, the power provided by the car will not be enough, and the car will shake.
1. Low temperature.
The temperature inside the engine is not enough, and the temperature of the fuel and lubricating oil is not enough. More fuel should be injected during cold start to meet the power requirements. The larger the gap between the spark plugs, the smaller the ignition energy. At low temperatures, the fuel atomizes poorly and the fuel requires higher ignition energy. If the car is used for a long time, the ignition gap of the spark plug can easily become larger, causing the ignition energy to decrease, thus affecting the power performance and causing the car to shake. In addition, aging of the ignition coil, aging of the spark plug high-voltage wire, or leakage will also reduce the ignition energy.
2. The mixing ratio is inappropriate.
Both open-loop and closed-loop control have the problem of inaccurate oil-gas mixture ratio. In closed-loop controlled cars, the minimum operating temperature of the oxygen sensor is 370 degrees Celsius. If the car has just been started, the oxygen sensor will not work because the temperature in the exhaust pipe is below 370 degrees Celsius. At this time, the ECU made a misjudgment and miscontrolled the oil-air mixture and ignition time through the actuator, thereby reducing the car's power output and causing jitter.
3. Carbon deposits on valves and air intakes.
If there is carbon deposits in the engine valves and air intakes, the ECU will make a wrong judgment, because the carbon deposits can absorb an appropriate amount of fuel (just like water flowing through a river bank, the soil will absorb water). In fact, the computer controls the hypothetical 100 parts of oil and gas to be ejected, but only 90 parts actually enter the cylinder (10 parts are absorbed by carbon deposits), so even if the remaining 90 parts of the mixed oil and gas are fully burned, the required power cannot be achieved, causing jitter. Inevitable.
4. The working conditions of each cylinder are different.
Similarly, the spark plugs of multi-cylinder engines will also have the above problems. After long-term use, the ignition gap and time control of the spark plug will be different, but the ECU cannot diagnose this deviation and still treats them equally, leading to practical and theoretical errors. Therefore, some cylinders produce too little power, causing judder. After the engine has been used for a long time, the gap between each cylinder liner and the piston will be different, that is, some gaps are large and some are small. During a cold start, without good oil lubrication, a cylinder with a large gap will easily leak a certain amount of high-temperature gas from the gap, thereby reducing power output.
5. The water temperature sensor is faulty.
The water temperature sensor was one of the important basis for the computer to judge the working status of the engine at that time. If the engine temperature is minus 10 degrees Celsius during a cold start, but the sensor "tells" the computer that the current temperature is 20 degrees Celsius, then the computer will inject fuel at 20 degrees Celsius. Of course, the amount of fuel will be small, and the engine will shake naturally.
6. Other factors.
The air flow meter is dirty, resulting in reduced air intake; the EGR (exhaust gas recirculation) valve is not working properly, and exhaust gas is introduced at idle speed; the idle speed motor controls the bypass air inlet to adjust the air intake, and the voltage may be low Not in place; the oil is too poor and cannot reach the corresponding calorific value, resulting in low combustion power output. The above four factors will cause poor cylinder combustion during cold start or waiting in neutral, causing engine shake.
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