Why does the car shake when starting?
2 Answers
The reasons why the car shakes when starting are: 1. The throttle is dirty or the fuel injector has excessive carbon deposits. When there is too much carbon deposit inside the engine, the gasoline sprayed by the cold start injector will be largely absorbed by the carbon deposits, resulting in an excessively lean mixture for cold start, making it difficult to start and causing idle shaking after cold start; 2. Poor working conditions of the ignition system and spark plugs can also lead to such fault phenomena; 3. If the engine carbon deposits have been cleaned, the throttle has been washed, and the spark plugs have been replaced, but the car body still shakes at idle, it is recommended to check whether the fuel supply pressure and the intake pressure sensor are normal. Abnormal fuel pump supply pressure or incorrect values and poor working conditions of the intake pressure sensor can also cause the car body to shake.
My car also had severe shaking during startup before, and this situation is actually quite common. The most likely culprit is the spark plugs - when they accumulate too much carbon buildup over time, the ignition becomes unstable, making the engine feel like it's shivering. Aging ignition coils can cause similar issues too, especially for cars that are seven or eight years old. Last time my car shook, it was because the throttle body was as dirty as if coated with grease sludge - with air unable to enter properly, the engine naturally struggled to breathe. Also check your engine mounts; those rubber cushions absorb vibrations, and when they deteriorate, the car shakes like a sieve. Finally, fuel quality matters - don't cheap out by filling up at questionable gas stations. I recommend going to a repair shop soon to read the trouble codes, before minor issues develop into major problems.
