What could be the cause of engine vibration when idling? WHY YOUR CAR SHAKES WHEN IDLING If your car feels smooth while driving but starts vibrating or shaking at a stoplight, something isn't right. At idle, the engine runs at its What could be the cause of engine vibration when idling? 2015 car vibrating at idle, RPM 500 WHY YOUR CAR SHAKES WHEN IDLING If your car feels smooth while driving but starts vibrating or shaking at a stoplight, something isn't right. At idle, the engine runs at its