What's with the engine humming without stepping on the gas pedal?

Abnormal sound of the car body is usually caused by the lack of rigidity of the car body, which leads to friction or jitter between the door and the frame when the car is running, or friction between steel plates caused by desoldering in some places. Sticking rubber strip on doors and windows or padding rubber on friction parts can reduce or eliminate abnormal sound. If this abnormal sound occurs, it is necessary to check and determine the fault point as soon as possible and replace the aging parts to solve it.