Signs of Bad and Fouled Spark Plugs Autolite How Do I Know If My Spark Plugs Need Replacing? Kelley Blue Book Engine vibrations can be alarming and indicate an underlying problem in your car. Here are the key causes of engine vibration while driving or idling: 1. Spark Plug Damage: Damaged spark plugs 5 Reasons Your Volkswagen Engine Is Shaking When Idle PPTX Car Vibrates When Idle: Major Causes and More dubizzle Reading a spark plug is a great way to check your engine's health. Mechanics often read spark plugs to diagnose fuel mixture, ignition, and engine condition. Here's a clear guide for