Why does the car shake at idle but not while driving?
1 Answers
Car shaking at idle but not while driving is usually caused by excessive carbon deposits or spark plug issues. It can also be due to unstable oil pressure or aging engine components. When the car is running in a natural state without shifting gears or accelerating, steering wheel vibration is referred to as idle shaking. Below are the common causes of idle shaking: 1. Excessive carbon deposits inside the engine: During startup, carbon deposits absorb some fuel, leading to an overly lean air-fuel mixture. Once the carbon deposits become saturated with gasoline, the engine starts operating normally. However, when the mixture is ignited, the gasoline absorbed by the carbon deposits is sucked back into the cylinder by vacuum pressure, resulting in an overly rich mixture. This alternating lean and rich condition causes engine shaking. 2. Prolonged use of spark plugs can lead to increased spark plug gaps or excessive carbon buildup on the ignition points. These issues can cause poor sparking or insufficient ignition energy, resulting in cylinder misfires, reduced power, and engine shaking. 3. If the throttle body, air filter, spark plugs, and carbon deposits are all in good condition, the fuel supply system should be checked. Insufficient fuel pump pressure can also lead to reduced engine power and shaking.
