What Causes Severe Idle Vibration?
2 Answers
Severe idle vibration can be attributed to the following main reasons: 1. Spark plug issues: If there is a malfunction in the car's ignition system spark plugs, it can lead to poor ignition system performance, inadequate spark plug firing, and other problems, resulting in unstable conditions such as vibration during idle. 2. Fuel quality problems: Poor fuel quality can damage engine performance, thus causing idle vibration issues. 3. Excessive engine carbon deposits: Too much carbon buildup inside the engine can cause the gasoline injected by the cold start injector to be largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making it difficult to start.
A few days ago, my car was shaking violently when stopping at a red light, with the entire seat vibrating, but it drove fine otherwise. After checking common causes, it's mostly due to old or dirty spark plugs not being replaced in time, which causes incomplete combustion and extra shaking. It could also be excessive carbon buildup clogging the fuel injectors, leading to poor fuel supply; or an air intake pipe leak, throwing off the air-fuel mixture ratio. I must remind everyone not to underestimate this issue—long-term shaking can easily damage the engine and waste fuel. I took apart the spark plugs myself and indeed found them blackened; replacing them fixed the problem. However, for those without experience, it's best to visit a professional repair shop for a thorough diagnosis—safety first.
