What Causes Severe Shaking When a Car Starts?
2 Answers
Severe shaking when a car starts may be due to suspension system failure, unstable oil pressure, or cold start issues. The specific reasons are as follows: Suspension System Failure: The suspension system is primarily responsible for filtering vibrations from the engine during operation. If the suspension system malfunctions, these vibrations can directly transfer to the steering wheel and cabin, affecting driving. When the engine is idling, turning on electrical systems inside the car can also easily cause shaking. The engine increases load due to the activation of electrical systems, leading to a drop in idle speed. To compensate for the shaking caused by the idle speed drop, the engine automatically raises the RPM. Unstable Oil Pressure: If the engine carbon deposits have been cleaned, the throttle body washed, and the oil pads replaced, but the car still shakes, it is recommended to check the fuel supply pressure and intake pressure sensors at a repair shop. Abnormal fuel pump supply pressure or incorrect intake pressure sensor readings and improper operation can all cause the car to shake. Cold Start: The main reason for car shaking during a cold start is insufficient fuel combustion, resulting in inadequate power. Low ignition energy means that during startup, when the temperature of fuel and lubricants is low, more fuel is needed to meet power demands. Over time, the electrode gap of the spark plug gradually widens, leading to reduced ignition energy and poor fuel atomization, which causes the car to shake. Additionally, aging ignition coils, high-voltage wires of the spark plugs, or electrical leaks can also reduce ignition energy.
I've been driving for quite some years and have encountered the issue of shaking during startup several times. Typically, manual transmission vehicles are most prone to this due to clutch wear. When the clutch disc slips or engages unevenly, the car body can shake violently the moment you release the accelerator. Another common cause is problems with the engine's ignition system, such as carbon buildup or aging spark plugs, or short circuits in the ignition coils, leading to unstable engine operation during low-speed starts. For automatic transmission vehicles, issues in the drivetrain like a faulty torque converter or contaminated transmission fluid can also cause shaking. It's also essential to check if the tire pressure is balanced, as mismatched tire pressure can make the car wobble during acceleration. Once this issue arises, it's best not to delay. I recommend getting a professional inspection at a specialized shop right away. Ignoring it could lead to increased wear and might even require a complete engine overhaul, which is both costly and frustrating. Regular maintenance should include checking the lifespan of the clutch disc and the condition of the spark plugs, especially for older models, which require closer attention.
