Why does the engine feel like it's vibrating when starting the car?
1 Answers
The most common cause of car shaking during startup is a dirty throttle body or excessive carbon buildup in the fuel injectors. 1. Excessive engine carbon deposits: When there's too much carbon buildup inside the engine, the gasoline sprayed by the cold start injector gets largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making ignition difficult. In this situation, the engine only starts easily after the carbon deposits become saturated with gasoline. After starting, the gasoline adsorbed on the carbon deposits gets drawn into the cylinders by the engine's vacuum suction for combustion, making the air-fuel mixture too rich. This alternation between lean and rich mixtures causes idle vibration after cold starts. 2. It might be normal: For vehicles with 3 cylinders or fewer, some shaking is normal - 3-cylinder engines naturally vibrate significantly. For 4-cylinder or larger engines, if the shaking is worse than usual, check the engine compartment for abnormalities, such as a cylinder not working or multiple cylinders performing poorly. Common symptoms include burnt spark plugs, excessive spark plug gaps, or loose connections - all of which can cause vehicle shaking. In such cases, stop the car and carefully inspect the spark plugs for integrity. If you have tools, you can remove the spark plugs for inspection. Other potential causes include poor fuel delivery or inadequate oil lubrication. If you can't handle these issues yourself, promptly visit a repair shop.
