What are the reasons for engine shaking when starting the car?
3 Answers
The reasons for engine shaking when starting the car are: 1. Low ignition energy due to cold engine temperature; 2. Inappropriate air-fuel mixture ratio; 3. Severe carbon buildup on engine valves and intake ports; 4. Uneven operation among engine cylinders; 5. Malfunctioning coolant temperature sensor. The function of the engine is: to convert the thermal energy of gasoline or diesel into mechanical energy by burning the fuel in a sealed cylinder, causing gas expansion that pushes the pistons to perform work. Engine maintenance methods include: 1. Regularly changing engine oil and filters; 2. Using lubricants of appropriate quality grades; 3. Periodically cleaning the radiator; 4. Regularly replacing air filters, oil filters, and fuel filters; 5. Maintaining good crankcase ventilation with regular cleaning; 6. Periodic cleaning of the fuel system.
That day, my car suddenly shook when starting, feeling like an earthquake. In fact, the most common cause is aging spark plugs, especially those that haven’t been replaced for several years. An unstable ignition system can make the engine unsteady, prone to stalling or shaking. Fuel system issues can also cause shaking, such as clogged fuel injectors leading to poor fuel supply, which is more noticeable with low-quality gasoline. A dirty air filter affects air intake, preventing the engine from functioning properly, especially in dusty environments. Carbon buildup over time can also impact cylinder combustion, leading to vibrations. Loose engine mounts are another factor, as worn metal parts transmit more vibrations. Regular maintenance should include frequent replacement of spark plugs and air filters, as well as checking the cleanliness of the fuel system. Ignoring this issue may increase fuel consumption and even lead to more severe damage. It’s recommended to visit a professional repair shop early to ensure driving safety.
With decades of driving experience, I can say startup vibrations mostly stem from ignition or fuel system failures. Worn spark plugs are the top culprit, while damaged ignition coils can also disrupt engine balance. Insufficient fuel pump pressure or clogged fuel lines often cause uneven fuel supply, especially triggering severe vibrations during cold starts. Vacuum hose leaks are another hidden issue affecting idle stability, and aging engine mounts transmit vibrations to the car body. Carbon buildup on valves or piston crowns induces shaking, posing serious risks if neglected long-term. The solution lies in regular maintenance: use additives to clean carbon deposits and replace spark plugs every tens of thousands of kilometers. Startup vibrations compromise driving comfort and safety, so prompt troubleshooting is essential to avoid roadside breakdowns.
