What Causes Car Body Shaking During Idling?

[VonNadia]

Car body shaking during idling is mainly caused by severe engine carbon deposits, ignition system issues, unstable oil pressure, aging engine components, etc. Below is a detailed introduction to car shaking during idling: 1. Ignition System Failure: Every time the ignition system is used, the spark plugs will wear out. Long-term use will lead to severe motor wear, causing the spark plug gap to increase, making it difficult to generate an arc, which increases the misfire rate. Inconsistent power output will cause the car to shake during idling. 2. Unstable Oil Pressure: The most common issue in the fuel supply system usually occurs with the fuel injectors. Excessive carbon deposits on the fuel injectors affect the fuel injection volume. When the fuel injection volume is too high or too low, it can easily cause the oil pressure to be too high or too low, leading to shaking during idling.

[LilahLynn]

Actually, body vibration at idle is quite common in vehicle usage, and I've encountered many similar issues. It's mainly caused by unstable engine operation. For example, a dirty throttle body leading to poor air intake, aging spark plugs affecting ignition efficiency, or clogged fuel injectors causing uneven fuel supply - these can all disrupt the engine's working rhythm. Also pay attention to the engine mounts, which are responsible for buffering engine vibrations; once they age and crack, vibrations get transmitted directly to the body. Another issue is carbon buildup, especially excessive carbon deposits in the combustion chamber and behind the valves - just like a person having difficulty breathing, this affects engine performance. If you notice vibration, I recommend first checking these four key points, especially for vehicles with over 100,000 kilometers on the odometer.

[IsabelaLynn]

As an ordinary car owner, I've experienced idle shaking before. At a red light, the car shook so violently that my phone could dance on the dashboard. The mechanic said there were several possible causes: the most common being worn spark plugs with insufficient ignition energy causing poor cylinder performance; secondly, a dirty air filter or intake pipe leak leading to improper air-fuel mixture; also, poor fuel quality can cause uneven fuel injection, especially after refueling at small gas stations; and aging engine mount rubber which shows immediate improvement when replaced. Later, I replaced all the spark plugs and engine mounts, which solved the problem. I recommend troubleshooting from simple to complex fixes.

[Connie]

From a physical principle perspective, idle shaking is essentially the transmission of engine operation imbalance to the vehicle frame. When there are issues with the ignition system, such as high-voltage wire leakage or excessive spark plug gap, the combustion timing of the air-fuel mixture in the cylinders becomes inconsistent; faults in the fuel supply system lead to varying mixture concentrations in each cylinder, resulting in uneven combustion forces; when the engine mounts, which serve as damping media, fail, the reciprocating vibrations of the engine at over 2000 RPM are directly transmitted to the body; wear on piston connecting rods can also cause unstable cylinder pressure. These conditions are particularly noticeable at low RPM because, at high RPM, the vibration frequency increases but the amplitude decreases, making it less perceptible.