What Causes Intermittent Idle Vibration in the Peugeot New 408?

[DiFelix]

Generally, when the hot engine idle speed drops below 800 rpm, vibration occurs. 1. Severe engine carbon deposits: The most common cause of car vibration is excessive carbon buildup in the throttle body or fuel injectors. When there's too much carbon inside the engine, the gasoline sprayed by the cold-start injector gets largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making ignition difficult. 2. Unstable fuel pressure: If you've already cleaned the engine carbon deposits, cleaned the throttle body, replaced gaskets and spark plugs, but still notice body vibration at idle, we recommend visiting a 4S shop to check the fuel supply pressure and intake pressure sensors. 3. Aging engine components: Car vibration can also be related to worn engine mounts. Engine mounts essentially serve as the engine's vibration damping system, absorbing minor vibrations during operation. If the engine mounts malfunction, these vibrations will transmit to the steering wheel and cabin, causing idle vibration.