Why does the car shake severely when driving at 100 to 120 km/h?
2 Answers
The reasons for severe shaking when the car is driven at 100 to 120 km/h are as follows: 1. Excessive carbon deposits: If there is severe carbon buildup in the engine cylinders, it can cause spark plug blockage and valve blockage, directly leading to shaking during idling. If the car's acceleration performance has significantly declined and the shaking is persistent, the engine cylinders need to be cleaned. 2. Fuel system failure causing unstable oil pressure: Unstable oil pressure can lead to inconsistent concentration of the air-fuel mixture, not only causing shaking but also resulting in unstable idling. First, consider replacing the fuel filter, then check the oil pressure that bypasses the fuel filter. If abnormal, the fuel pump may be the issue. 3. Aging engine mounts: If the engine shaking becomes increasingly severe but the power does not weaken accordingly, it is mostly due to problems with the engine mounts. 4. Misfire or cylinder failure: The issue lies with the engine ignition coil or spark plugs. If the ignition coil fails or the spark plugs cannot fire for some reason, the car will experience shaking.
Last time I was on the highway, I encountered the same issue. When the speed reached around 110 km/h, the steering wheel shook violently. After inspection, it turned out the tire dynamic balance wasn't properly done, with two of the four wheel balancing weights missing. By the way, warped rims can also cause this, especially on roads with many potholes. Additionally, if the CV joint is worn or the driveshaft is bent, the shaking will be accompanied by seat vibration. I suggest getting a dynamic balance check first—it only costs a few dozen bucks. If the shaking persists, then inspect the chassis components. Warped brake rotors can also cause vibrations. Remember, never ignore high-speed shaking—it's dangerous to keep driving like that.
