What Causes Sudden Engine Shaking During Ignition?
2 Answers
There are several reasons why a car may experience slight shaking during startup, including a dirty throttle body or increased spark plug gap. Below are detailed explanations of the potential causes of engine shaking during startup: Dirty Throttle Body: A dirty throttle body or excessive carbon buildup in the fuel injectors can cause slight shaking after the car starts. If disassembling the intake tract for cleaning is not feasible, you can use a no-disassembly fuel system cleaning device, though the results may not be as effective as a full disassembly. Increased Spark Plug Gap: After prolonged use, the spark plug gap may increase. Depending on the situation, you can clean the spark plugs or adjust their gap to continue using them.
I've been driving for over twenty years and have encountered several instances where the car suddenly shakes during ignition, especially during cold starts. I remember one winter morning when I turned the key to start the car, the entire steering wheel shook violently—I almost thought it was going to stall. There are quite a few reasons for this: the most common is aging spark plugs or failing ignition coils, causing uneven sparks and resulting in shaking; clogged or dirty fuel injectors leading to insufficient fuel supply can also cause this; a dirty air filter restricting airflow, making it hard for the engine to breathe, can similarly cause shaking; severe carbon buildup over time in the combustion chamber can affect the compression ratio; and faulty sensors like the crankshaft position or throttle position sensors can send erratic signals, leading to poor control. When this happens, I suggest not forcing the car to run—pull over safely and call a tow truck to take it to a repair shop. For prevention, regularly replacing spark plugs and cleaning the fuel system can reduce such issues. Don’t underestimate the shaking—ignoring it could lead to engine or other component damage, and the repair costs would be much higher.
