What Causes Shaking in an Automatic Transmission Car After Starting?

[AriannaMarie]

There are several reasons why an automatic transmission car may shake when starting: 1. The throttle body is too dirty, causing uneven air intake and resulting in shaking. 2. The fuel system is obstructed, leading to insufficient fuel supply at low throttle and causing uneven operation of the engine cylinders, resulting in shaking. 3. The transmission is not functioning properly. If the car shakes when starting but runs normally afterward, the possible causes include: 1. A dirty throttle body causing uneven air intake and shaking. 2. A clogged fuel system leading to insufficient fuel supply at low throttle, causing uneven operation of the engine cylinders. 3. Damaged high-voltage wires or spark plugs, resulting in a cylinder not firing and causing the engine to run unevenly and shake.