When the temperature at the time of use is low, it will feel like a car that is likely to stall for a while after powering on and opening the valve or charge valve of the manifold for a while. Bass buzzer sounds and the body vibrates greatly and shakes. (I have never stopped) I will correct it after a while. It seems that there is no problem when you move nothing and when you use it when the temperature is high. This is only for summer. Is this normal? Everything cheap, it is a product we can not recommend too much.