What Causes Engine Shaking When Starting an Automatic Transmission Car?
2 Answers
Automatic transmission car engine shaking when starting is caused by: 1. Worn or loose engine mounts; 2. Engine misfire; 3. Severe carbon buildup in the engine; 4. Tire bulges or wheel hub deformation; 5. Intake pipe or EGR valve leaks; 6. Loose chassis components. Methods to address engine shaking include: 1. Reading fault codes or data streams to eliminate sensor faults; 2. Checking if the exhaust gas recirculation valve is faulty; 3. Inspecting spark plugs, high-voltage lines, ignition coils, fuel injectors, timing marks, fuel pump pressure, and cylinder pressure; 4. Checking the idle control valve for issues and cleaning the throttle body and idle control valve.
When my automatic transmission car starts, the engine shakes severely, and the most common cause is excessive carbon buildup in the engine. Carbon deposits clog the cylinders, leading to incomplete combustion, which causes shaking. Additionally, aging spark plugs often result in this issue, as uneven ignition makes the engine wobble. If the fuel quality is poor or water has entered the fuel system, clogging the fuel injectors, unstable fuel supply can also cause shaking. Another reason is worn engine mounts, which lose their damping effect, transmitting the entire engine's vibration to the chassis. This is more noticeable during cold starts when the oil is too thick or the idle control valve is dirty, restricting air intake. I recommend taking the car to a repair shop first to check the spark plugs and air filter. If the problem persists, clean the throttle body and fuel injectors or inspect the ignition coils. Don’t neglect regular maintenance, such as cleaning carbon deposits every two years to avoid sudden breakdowns disrupting travel. Addressing the issue early is crucial; otherwise, minor shaking could lead to costly major repairs.
