What Causes the Idle Needle to Shake?

[DiBrandon]

The cause of the idle needle shaking may be due to a dirty throttle valve, excessive carbon buildup inside the engine, etc. Dirty Throttle Valve: After the car starts, the engine is in idle state, and air continuously passes through the throttle valve into the cylinders to mix with gasoline for combustion. If the throttle valve is too dirty, it will reduce the air intake into the intake manifold, and this insufficient air intake will fail to achieve the proper air-fuel ratio, leading to engine shaking. Excessive Carbon Buildup Inside the Engine: Prolonged use of the engine can result in excessive carbon buildup, causing the engine to shake. During operation, the internal working environment of the engine is very harsh. Over time, carbon deposits accumulate around the intake valve ports. This can eventually lead to poor sealing of the valves, and in severe cases, engine shaking. In such cases, it is necessary to remove the intake manifold and clean the carbon deposits outside the valves.