What Causes Engine Shaking That Returns to Normal After Restarting?

[OMatteo]

When the engine shakes during a cold start but returns to normal after restarting, it indicates carbon buildup in the engine. This could be due to carbon deposits on the throttle body or spark plugs, or excessive spark plug gap. Engine Carbon Buildup Issues: Carbon deposits may accumulate in the cylinders, throttle body, spark plugs, intake pipes, and other areas closely related to engine power output. Excessive carbon buildup reduces ignition energy and intake efficiency, leading to symptoms like engine shaking and poor acceleration. Excessive Spark Plug Gap: This can cause increased fuel consumption, weak driving performance, and failed emissions tests. Cleaning or replacing the spark plugs is necessary.