What Causes Engine Shaking During Cold Start?
4 Answers
Reasons for engine shaking during cold start are as follows: 1. Incorrect Air-Fuel Ratio: Improper air-fuel mixture occurs when the fuel-air mixture is inaccurately proportioned, existing in both open-loop and closed-loop control systems. In vehicles with closed-loop control, the oxygen sensor's operating temperature is 370°C. 2. Carbon Deposits: Carbon buildup on valves and intake passages. If carbon deposits form on engine valves and intake passages, they can absorb a certain amount of fuel, causing the ECU to make incorrect judgments. 3. Cylinder Conditions: Uneven cylinder performance. After prolonged engine use, the clearance between each cylinder liner and piston will vary. Larger clearances in certain cylinders allow high-temperature gases to leak, reducing power output. 4. Faulty Coolant Temperature Sensor: If the coolant temperature sensor malfunctions - for example, when the actual engine temperature is -10°C during cold start but the sensor reports 20°C to the ECU - the computer will inject fuel based on 20°C conditions, resulting in insufficient fuel supply and causing shaking.
I've been driving this old car for a few years. One winter morning when starting it, it shook like an earthquake. After checking information and consulting mechanics, I learned that cold start shaking could be due to worn spark plugs or excessive carbon buildup, causing ignition issues. Dirty throttle body restricting air intake or clogged fuel injectors causing uneven fuel spray are also main culprits. Worse yet, if the engine mounts are aged or broken, the car becomes unstable. Other possibilities include faulty ignition coils or insufficient fuel system pressure. I tried cleaning the throttle body myself, which only cost a few dozen bucks to fix. Regularly checking spark plug lifespan helps avoid roadside breakdowns. Ignoring these issues can damage the engine and waste fuel, creating real trouble. Timely maintenance is essential for peace of mind.
As an experienced driver, I've encountered similar issues. Cold start shaking is usually caused by spark plugs reaching the end of their lifespan or carbon buildup affecting ignition performance. Aging ignition coils, poor relay contact, or unstable fuel pump supply can also be the culprits. A dirty throttle body or intake manifold leaks can lead to significant engine vibration. If the engine mounts are deformed or broken, the shock absorption fails directly. It's recommended to first check the condition of the spark plugs; if they appear blackened, replace them. Cleaning the fuel injection system to prevent clogging and taking preventive measures can save you trouble. If you notice shaking, avoid driving hastily. Drive at low speeds with safety as the priority, and visit a repair shop as soon as possible to prevent the situation from worsening.
I have some knowledge about cars. Cold start shaking is commonly caused by aged spark plugs with carbon deposits, ignition system failures such as faulty coils, excessive throttle body dirt obstructing air intake, or clogged fuel injectors causing irregular fuel spray. Worn engine mount cushions can also amplify the shaking. Abnormal sensors like the crankshaft position sensor can affect startup as well. Start the inspection with the spark plugs—replace them if the gap is too wide or resistance is abnormal. Cleaning the throttle body is cost-effective and yields good results. Long-term neglect of engine vibrations increases damage and fuel consumption. While repairs aren't complicated, they ensure safety.
