What Causes Engine Shaking After Starting the Car?

[DeDerek]

1. Excessive Engine Carbon Buildup: When there is too much carbon buildup inside the engine, the fuel injected by the fuel injector during startup is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture and difficulty starting. Only when the carbon deposits become saturated with fuel will the vehicle start more easily. 2. Air Filter: If not replaced in time, a clogged air filter can cause insufficient air intake, lowering the engine idle speed and leading to engine shaking. 3. Low Ignition Energy: During a cold start, the engine's internal temperature is insufficient, requiring the fuel injector to spray more gasoline to meet power demands. The fuel needs higher ignition energy, but increased spark plug gap reduces ignition energy, affecting performance and causing the vehicle to shake. 4. Abnormal Coolant Temperature: High engine coolant temperature can cause premature ignition timing, altering the air-fuel mixture ratio and thinning the engine oil viscosity (reducing lubrication). Causes of abnormal coolant temperature include low coolant levels, a stuck thermostat, fan malfunction, or inaccurate temperature control switch settings. 5. Carbon Buildup on Valves and Intake Ports: Carbon deposits on the engine's valves and intake ports can lead to shaking. 6. Clogged Fuel Injectors: Blocked fuel injectors result in uneven fuel distribution among cylinders, causing inconsistent engine operation and resulting in shaking.

[Saul]

After starting the car, the shaking made me first think of engine or ignition system issues. It could be caused by aging spark plugs leading to unstable ignition, or clogged fuel injectors resulting in uneven air-fuel mixture. If the fuel system isn't flowing smoothly during engine idling, this can also happen, and prolonged conditions may increase fuel consumption. It's recommended to check the spark plugs and fuel filter, replacing them if necessary. If the shaking occurs frequently, also pay attention to whether the engine mounts are loose, otherwise the vibration will spread throughout the car body, making driving uncomfortable. Early intervention can avoid major repairs, saving both trouble and effort.

[DelStephen]

I've experienced severe shaking after starting the car, which turned out to be caused by a dirty air filter restricting airflow – the engine wasn't getting enough 'food' to run smoothly. Another common issue is excessive carbon buildup in the cylinders, which affects fuel combustion efficiency. It's best to develop the habit of regularly cleaning the throttle body and checking fuel quality, avoiding low-grade gasoline. Minor shaking might allow you to drive for a while, but when it becomes severe, you should visit a 4S shop for inspection to prevent more expensive and troublesome repairs later, which could disrupt your daily commute.

[Robin]

Engine shaking after starting is not a trivial matter, as it may indicate hidden safety hazards. For example, faulty ignition coils or spark plugs can cause engine misfires. While it may seem fine when parked, driving on the road could lead to sudden stalling and potential accidents. It is recommended to immediately check if the warning light is on, and pay extra attention if there are any unusual noises. Avoid attempting DIY fixes and promptly visit a repair shop for a comprehensive diagnosis, prioritizing driving safety above all else.