What could be the cause of engine vibration when idling? Why Does Your Engine Vibrate at Idle? Noticing your engine shaking or vibrating while idling? This could mean something isn't right under the hood. Here's what might be causing it and how 10 Causes For Shaking Vibrating The Car Engine at Idle While Stopped 2015 car vibrating at idle, RPM 500 Is your car vibrating when idle? Here's when you should be worried