What Causes Severe Engine Idle Vibration?

[CatherineRose]

Severe body vibration during idle is primarily caused by heavy carbon buildup in the engine, leading to dirty throttle bodies or excessive carbon deposits in fuel injectors. The lower the temperature, the more fuel is required for cold starts, and carbon deposits significantly affect the smoothness of cold starts. Solution: Clean the fuel system and check if the idle control valve has carbon buildup that needs cleaning. For ignition system issues, inspect the condition of spark plugs, high-voltage wires, and ignition coils. Poor ignition system performance or weak spark plug firing can also cause such symptoms. Abnormal fuel pump pressure or malfunctioning intake pressure sensors may also trigger body vibration. Vibration locations: Distinct engine vibration can be felt from beneath the seats, with slight steering wheel vibration. Opening the door and placing a hand on it will also clearly reveal engine vibration.