Why does the car shake violently when it is just started?
2 Answers
The reasons for violent shaking when the car is just started are as follows: 1. Poor fuel quality: Inferior fuel has poor volatility, and the engine block temperature is low when starting a cold car, causing the fuel injected into the cylinder to not fully mix with the air, resulting in difficulty starting and severe body shaking. 2. Carbon deposits in the engine valves and intake pipes: Carbon deposits can absorb an appropriate amount of fuel, causing the electronic control unit to make incorrect judgments, failing to provide the power needed for car startup, leading to shaking. 3. Spark plugs: The gap between the spark plug electrodes gradually increases, the ignition energy decreases, and the fuel atomization is poor, causing the car body to shake immediately after starting.
I often encounter the issue of severe shaking when starting the car, which usually has several common causes. Unstable engine ignition system is the primary suspect, such as aging spark plugs or worn ignition coils, which fail to properly ignite the fuel, causing the car to tremble like it's dancing. Next is the fuel supply problem—if your fuel injectors are clogged or the fuel pump pressure is insufficient, fuel can't enter the combustion chamber, leading to unbalanced engine operation. Don’t forget the air flow sensor malfunction; once it fails, the oxygen-to-fuel ratio gets disrupted, making the car particularly sensitive during cold starts. Vacuum leaks are also a big deal—if the intake pipe seal is loose, air escapes randomly, causing the engine to run unevenly. This kind of shaking is no small matter—it wastes fuel, damages engine components, and over time, major repairs become even more expensive. I recommend going to a professional auto shop as soon as possible for a comprehensive check, such as a diagnostic computer scan, to avoid worsening the problem.
