Is it normal for the engine to make a particularly loud noise when idling?

Idle engine is noisy, and the car feels wobbly because the engine is unstable. Check whether the cylinder pressure, ignition spark energy, throttle sensor, idle motor and engine foot pad are normal. It may also be related to air intake. Jitter is caused by engine deflagration, and piston carbon deposition can also cause this phenomenon. Check the fault code, and if there is no fault code, check the exhaust system.

If you want to hear the sound of the engine, you must find a quiet place, because the sound insulation effect of better cars is ideal now. If you don't look at the engine tachometer and don't know that the car is in a burning state, you may turn the key and ignite again. When monitoring the engine, generally follow the following steps:

1. During engine starting, the starting motor should not have harsh sound; The engine idle "chug sound" is even and there is no abnormal sound; The idle speed is stable at about 850 rpm (please refer to the automobile manual for specific stable idle speed values).

2. Gently step on the accelerator to slowly increase the engine speed, and there should be no noise in the process. Individual models will vibrate at a fixed speed, that is, the whole body will vibrate (if the vibration of * * * is very slight, it should be normal), and the vibration phenomenon of * * * after this speed should be eliminated; After the engine speed exceeds the maximum power point speed, the sound is generally obvious, but there should be no metal rubbing sound.

3. Press the accelerator pedal quickly, and the sound of engine power improvement should be smooth and without stagnation; Carefully distinguish the engine speed sound. The main sources of noise are: valve sound (usually "click" sound), if it is large, it is suspected to jack up the valve; All kinds of belt rotation sounds (generally squeaky sounds), if loud, may be the friction between the belt and the body; It is doubtful whether the engine makes other rubbing sounds to cover up the sudden sound.

4. Find a suitable place and drive the vehicle for 5- 10 minutes under complicated road conditions. After stopping, the idle speed should remain unchanged and the sound should be the same as before.