How To Diagnose An Idle Vibration In Your Mercedes Is your car vibrating when idle? Here's when you should be worried Engine shaking while idling? That small vibration is usually worn engine mountsand it only gets worse with time. Left too long, it can lead to extra strain on your engine, gearbox, and even your what's the issue with idle vibration at around 800 rpm? What could be the cause of engine vibration when idling? At Idle And Red Lights Im Getting A Small Vibration Is That Normal For A 2018 Terrain SLT 2.0, Dont Here Any Odd Noises But Seems Like It Shouldnt Only Have Had The Car A Few Days. Brandon