Why does the car shake when warm but not when cold?
3 Answers
Reasons for engine shaking when warm are as follows: 1. Injector malfunction: Uneven fuel injection or poor atomization from the injectors leads to imbalanced power output among cylinders. 2. Fuel pressure issues: Low pressure causes poor fuel atomization or linear fuel spray (in severe cases just dripping), reducing injection quantity and creating a lean mixture. High pressure increases actual fuel injection, creating a rich mixture. 3. Spark plug problems: Incorrect spark plug gap; eroded or damaged electrodes; carbon buildup on electrodes; cracked spark plug insulators.
I've been thinking about the issue of normal cold starts but engine shaking when hot. The most common cause is aging or damaged engine mounts, where the gaps increase when hot, leading to vibrations. Ignition system problems can also be a factor, such as excessive carbon buildup on spark plugs—they might work when cold but fail to ignite properly when hot due to uncontrolled electrode gaps. Insufficient fuel supply is another possibility, like clogged fuel injectors causing unstable pressure and uneven fuel delivery. Sensor failures, such as degraded thermal performance of the crankshaft position sensor, can confuse the ECU and lead to inaccurate adjustments. Early diagnosis is crucial; otherwise, prolonged driving can accelerate component wear, increase abnormal engine wear, and raise repair costs. Start by checking the looseness of the mounts and the condition of the spark plugs, then inspect the cooling system's heat dissipation efficiency. Don't cut corners or delay repairs, as it could cause deeper damage to your car.
I find this issue quite concerning. If the car shakes when cold but runs normally when warm, there might be impurities in the fuel system, or a clogged fuel filter affecting fuel supply. Engine oil viscosity being too high or uneven distribution can lead to insufficient lubrication and increased friction, causing shaking. Excessive carbon buildup in the throttle body can make it less responsive. Safety-wise, it's important to note that severe shaking can lead to loss of control, so it's best to stop and check before driving again. Check if the air filter is dirty, as it can affect the air-fuel mixture, making it too rich. Regularly changing the engine oil and air filter can prevent many of these issues. Addressing the problem early saves money and hassle, ensuring a safe and worry-free ride for family and friends.
