What Causes Engine Shaking When Cold?
2 Answers
Engine shaking when cold is caused by: 1. Low temperature: The exhaust pipe and oxygen sensor are cold, preventing the vehicle's ECU from obtaining accurate data promptly, leading to errors in ignition and air-fuel mixture control, which weakens the engine's power output; 2. Carbon buildup in the engine: Carbon deposits on the throttle body have adhesion, preventing the fuel injection from reaching the required gasoline amount for combustion; 3. Worn spark plugs: Different ignition gaps cause power deviations among the cylinders. Methods to address cold engine shaking include: 1. Letting the car idle after a cold start to allow the engine temperature to rise; 2. Cleaning the throttle body and fuel injectors; 3. Replacing the spark plugs.
I've been driving for twenty years and have encountered cold start shaking many times, usually due to aging or dirty spark plugs causing uneven ignition. Especially on winter mornings, when the spark plug gap is larger and ignition efficiency is low, the engine tends to shake. Additionally, the fuel injection system might be problematic; clogged fuel injectors can make the air-fuel mixture too rich or too lean, making the car more prone to vibration during cold starts. Excessive carbon buildup can also cause this, such as throttle body deposits affecting air intake, leading to immediate shaking upon startup. Worn engine mounts with poor damping effects can also transmit noticeable vibrations to the car body. It's recommended to warm up the car for a few minutes in the morning, check the condition of the spark plugs, and regularly replace coolant and engine oil to reduce shaking occurrences.
