What Causes Car Vibration at Idle Speed?
2 Answers
The causes of car vibration at idle speed can be attributed to the following 5 points: 1. Engine intake pipe leakage: The intake system contains numerous intake manifolds or various valves. If there is a leak, unwanted gases may enter, causing the concentration of the air-fuel mixture in the intake manifold to become too high or too low, ultimately leading to intermittent engine vibration or weak performance at idle speed. 2. Fuel system blockage or malfunction: Due to a blocked fuel tank vent, clogged fuel tank switch, fuel filter, or fuel line between the tank and the carburetor, the vehicle may not receive the required amount of fuel at idle speed, resulting in a lean mixture and weakened engine power output, causing idle vibration. 3. Idle control valve failure: The idle operation of an electronically fuel-injected engine is mostly controlled by the idle control valve. The ECU adjusts the opening of the idle control valve based on signals such as engine speed, temperature, and throttle position to maintain stable idle speed. If the valve malfunctions, it can lead to uneven air distribution, causing fluctuating engine power at idle speed and resulting in vehicle vibration. 4. Excessive engine carbon deposits: When there is excessive carbon buildup inside the engine, the vehicle's ignition energy decreases, and intake efficiency drops, ultimately leading to unstable engine power output, idle vibration, and poor acceleration. 5. Poor fuel injector atomization or partial blockage: Under cold idle conditions, the quality of the air-fuel mixture deteriorates or the fuel injection volume is too low, causing the mixture to become too lean, resulting in unstable idle speed or engine vibration.
Engine vibration at idle I've encountered this issue several times during vehicle use, with the most common cause being ignition system problems. Worn spark plugs or faulty ignition coils can cause uneven firing, leading to increased engine vibration. Carbon buildup is another troublesome issue; deposits on intake valves or in the combustion chamber can affect air-fuel mixture combustion, resulting in shaking. If the engine mounts are aged or cracked, their vibration-dampening effectiveness decreases, allowing vibrations to transfer directly to the vehicle body. Additionally, a dirty throttle body or air leaks can cause uneven airflow, which may also trigger vibrations. It's recommended to first check if the spark plugs are dirty or have reached the end of their service life. If replacing them doesn't significantly improve the situation, then inspect the engine mounts and clean carbon deposits from the throttle body. Addressing these issues early can prevent more severe engine damage.
