What Causes Engine Vibration During Startup?
2 Answers
Below are the reasons for engine vibration during startup: 1. When driving, engine vibration may be caused by a dirty throttle valve or excessive carbon deposits in the fuel injector and intake manifold. In cold conditions, carbon deposits can absorb some of the fuel, and if the fuel does not completely enter the cylinder for combustion, it can lead to unstable idling and difficulty starting. 2. It may be caused by damage to the inner CV joint. If pits form on the inner wall of the CV joint where it frequently contacts the outer race of the needle roller bearing, the engine and transmission may perform a slight lateral tilting motion during rapid acceleration, changing the position of the force application point. As the CV joint rotates, this force application point continuously shifts back and forth along the axial direction, generating a force that pushes the vehicle body alternately to the left and right, creating a sensation of vibration. Below are the solutions for engine vibration during startup: 1. Replace the damaged inner CV joint or axle shaft. 2. Have the vehicle inspected and repaired at a 4S shop or professional repair facility.
That day I encountered engine start-up shaking, and my first thought was an issue with the ignition system. Worn spark plugs or faulty ignition coils are the most common culprits, causing uneven ignition energy and severe engine shaking. Next are fuel system problems, such as clogged fuel injectors or unstable fuel pump pressure, where incorrect fuel injection affects combustion balance. Then there's the intake system—like a dirty air filter or a leaking manifold—where uneven air intake worsens the shaking. Also, don’t overlook damaged engine mounts, which transmit vibrations directly to the car body. I remember one time it shook for half a month before finally diagnosing burnt-out spark plugs; replacing them immediately smoothed things out. If left unfixed, this issue can lead to loss of control at high speeds, so it’s crucial to regularly inspect spark plugs and clean the throttle body as a precaution. Routine maintenance should focus on the ignition system and fuel line condition.