Why is the car shaking violently when starting?

[LaLeah]

Severe shaking during vehicle startup could indicate an engine malfunction. The following are potential faults: 1. Engine mechanical failure: Uneven cylinder pressure across cylinders. 2. Intake system malfunction: Intake pipe leaks, excessive carbon buildup on intake valves and pipes, excessive dirt on throttle body and intake pipe walls. 3. Engine management system failure: Incorrect coolant temperature or intake air temperature signals, wiring faults. 4. Ignition system malfunction: Excessive carbon buildup on spark plugs or incorrect gap, leakage in high-voltage wires or distributor cap, damaged ignition coils. 5. Fuel delivery system failure: Fuel injector sealing issues or clogging due to excessive internal carbon deposits.

[AryaLee]

I remember when I first started driving, one morning my car shook violently upon starting, as if it was about to fall apart. After some thought, it might have been due to old spark plugs not being replaced on time, affecting ignition efficiency; or too much carbon buildup clogging the intake, leading to incomplete combustion; or aging and loosening engine mounts that exacerbated the engine's shaking. Regular maintenance is crucial, like checking spark plugs and air filters every 20,000 kilometers, and using high-quality fuel to reduce carbon deposits. I suggest not ignoring small issues—driving with a shaking car is not only uncomfortable but also accelerates part wear. It's best to visit a professional repair shop early. They can quickly diagnose the problem with a scanner, and replacing a few parts might only cost a few hundred dollars, ensuring safe driving.

[EloiseAnn]

From a technical perspective, severe vehicle shaking during startup is often caused by ignition system failures, such as unstable ignition due to worn spark plugs or insufficient power supply from faulty ignition coils. The fuel system also plays a role—clogged fuel injectors or abnormal fuel pump pressure can lead to inconsistent combustion. Additionally, damaged engine mounts are a common culprit, transmitting vibrations to the body upon startup. Carbon buildup should not be overlooked, as it dirties the intake tract and throttle body, disrupting airflow. It's recommended to first use an OBD scanner to read trouble codes and pinpoint the core issue. For DIY checks, inspect spark plug color or look for cracks in the mount rubber. Avoid delaying repairs, as prolonged shaking can escalate into engine damage, resulting in higher costs.

[DeSadie]

When the car shakes violently during startup, I recommend checking the basics first: 1. Inspect the spark plugs for oxidation or incorrect gaps, and replace if necessary; 2. Check if the air filter is clogged, affecting air intake; 3. Examine the engine mounts and brackets for aging cracks. Regular maintenance like oil changes can prevent carbon buildup, and issues with the fuel pump or throttle body can also cause shaking. If abnormalities are found, drive directly to a repair shop for diagnosis—don't push through. Fixing these problems will immediately restore smooth operation.