What are the causes of car engine shaking during cold start?
2 Answers
The causes of car engine shaking during cold start are: 1. Engine mechanical failure, uneven cylinder pressure in each cylinder; 2. Intake pipe leakage, excessive carbon deposits on intake valves and intake pipes, or excessive dirt on throttle valves and inner walls of intake pipes; 3. Abnormal water temperature and intake air temperature signals or circuit faults; 4. Excessive carbon deposits on spark plugs or damaged ignition coils; 5. High-voltage wire leakage or distributor cap leakage; 6. Excessive internal carbon deposits in fuel injectors causing poor sealing or blockage. The solutions for car engine shaking during cold start are: 1. Check for engine faults or clean engine carbon deposits; 2. Check the working condition of spark plugs and ignition coils; 3. Check for any circuit issues.
I've been driving for nearly twenty years, and my sedan always shakes during cold starts, especially on winter mornings. The most common cause is excessive carbon buildup in the engine. Carbon deposits on pistons or intake valves lead to uneven fuel-air mixture and incomplete combustion, resulting in severe shaking. Aged spark plugs are another reason—when the electrode gap widens, ignition becomes unreliable, causing sputtering sounds upon startup. Fuel system issues shouldn't be overlooked either: clogged injectors disrupt fuel flow, or a weak fuel pump fails to deliver adequate pressure. Worn engine mounts also contribute, as hardened rubber loses its damping effect, making the whole car wobble during cold starts. I once faced this—diagnostics showed worn spark plugs needed replacement, and adding fuel system cleaner helped significantly. Regular maintenance for carbon cleaning and ignition system checks is highly recommended.
