The car trembles when idling on the spot, and it is normal after a little gas. What is going on?u0026#x

The car trembles when idling on the spot, and it is normal after a little gas. What is going on? I believe that many people’s cars have encountered such a situation, and I can’t tell you one reason when I go to the repair shop. I usually tell you that it’s okay, just drive it like this! In fact, the reason for this phenomenon is very simple, that is, the power of the engine is insufficient.

When a car engine is running, there are many friction pairs inside, such as pistons, piston rings and cylinders, valves and Camshafts, gear pairs, etc., will generate a certain amount of friction, in addition to the tension of the valve spring, the compression resistance of the cylinder, etc., which are collectively referred to as the running resistance of the engine. Running resistance will hinder the operation of the engine, so the engine must split a part of the power to overcome these running resistances. Generally speaking, the engine needs to take out about one-third of the power to overcome its own running resistance.

When the engine is idling, in addition to driving some accessories, the remaining power is almost all used To overcome internal resistance. Therefore, the idling speed of the engine is carefully adjusted, which can ensure the smooth operation of the engine at idling speed without excessively high speed, which will waste the power of the engine. Generally speaking, an engine with a larger displacement and a larger number of cylinders has a lower idle speed, and vice versa. For example, our common four-cylinder engine idling speed is generally around 800 rpm, the six-cylinder engine idling speed is generally around 600 rpm, and the three-cylinder engine idling speed is generally around 1000 rpm.

If the engine is due to some reasons, such as dirty throttle, carbon deposits in the engine, poor ignition system, and fuel supply system failure , Air intake manifold leaks, severe engine aging and wear, excessive oil viscosity, etc., will cause the engine's power to drop, which is not enough to overcome the running resistance, and the engine will experience jitter, uneven running or even flameout. At this time, as long as we step on the accelerator a little bit to let more air enter the engine, and at the same time inject a little more oil, the power of the engine will increase, enough to overcome the running resistance of the engine, and the engine will not shake.

The engine jitter can be automatically adjusted within a certain range, such as cold car high idle speed, throttle adaptive and so on. If the adjusted threshold is exceeded, it needs to be repaired. The focus of solving the problem is on how to improve the engine power, such as cleaning the throttle, checking the fuel pressure, checking and replacing the ignition coil and spark plug, etc. If it still does not work, check the cylinder Pressure to see if the failure is due to mechanical reasons.