The first low frequency * * * vibration, idle speed and below 2000 rpm will have * * * vibration. This reason is mainly caused by unreasonable design of exhaust back pressure drum and unreasonable matching of engine speed. Or there is a problem with the flexible connection point of the head.
The second high-frequency vibration is above 2000 rpm or above 3500 rpm. The higher the rotating speed, the greater the vibration. This is generally because the car's sound insulation or shock absorbing ears are too hard, or the exhaust pipe material is too thin and the inner diameter of the exhaust pipe is rough.
The third hard connection vibrates, which exists at any speed. Generally, the installation is unreasonable, and there are hard-connected fixed points in other places except the lifting lug. It is often caused by working on modified exhaust pipes with mismatched models.