What Causes Vehicle Body Shaking at Idle Speed?
2 Answers
There are primarily four major reasons for vehicle body shaking at idle speed: 1. Severe engine carbon buildup. When there is excessive carbon buildup inside the engine, the gasoline sprayed by the cold start fuel injector will be largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making it difficult to start. The solution is to clean the fuel system and check if the idle speed control valve has carbon buildup that needs cleaning. 2. Ignition system issues. Inspect the working condition of the spark plugs, high-voltage wires, and ignition coils. The solution is to check if the spark plugs have excessive carbon buildup and replace them if necessary. 3. Unstable fuel pressure. If you have already cleaned the engine carbon deposits, cleaned the throttle body, replaced the fuel pads and spark plugs, but still notice body shaking at idle speed, you need to visit a 4S shop to check whether the fuel supply pressure and intake pressure sensor are functioning properly. Abnormal fuel pump supply pressure or incorrect readings and poor performance of the intake pressure sensor can all cause body shaking. The solution is to check the fuel pressure and replace components if necessary. 4. Aging engine components. Engine mounts are the shock absorption system of the engine, responsible for absorbing minor vibrations during engine operation. If the engine mounts are faulty, these vibrations will be transmitted to the steering wheel and the cabin, causing shaking at idle speed.
I've encountered this situation several times. When idling, the car body feels like it's shaking, usually because the engine has severe carbon buildup, and the throttle is clogged with oil residue, causing poor air-fuel mixture. Also, if the spark plugs haven't been replaced for years, the ignition becomes unstable. Another common issue is aging or loose engine mounts, which directly makes the car body shake more noticeably when parked. I suggest you try checking the condition of the mounts yourself to see if there's any obvious damage. Alternatively, drive to a repair shop for a throttle cleaning—it's not expensive but very effective. Once, my car shook badly at a highway service area, but after cleaning, it was fine and even saved fuel.
