Why does the car shake when starting?
2 Answers
There are several reasons why a car may shake when starting: 1. It could be due to severe carbon buildup inside the engine, making it difficult to start the vehicle and causing idle shaking. 2. There might be an issue with the vehicle's ignition system. It's necessary to check the spark plugs and high-voltage wires. If the ignition system isn't functioning properly, it can lead to idle shaking or difficulty starting. 3. Unstable fuel pressure in the vehicle's fuel system. If the fuel pump can't supply fuel to the vehicle normally, it may result in poor fuel atomization or failure to open the fuel injectors, causing cylinder misfire shaking or failure to start. 4. Insufficient engine cylinder pressure. Over time, the vehicle's engine may have exceeded its service life and can no longer function properly, leading to intermittent idle shaking. In such cases, immediate repair at a service center is necessary.
Last time my car had the same issue, it shook like dancing when starting. The main problem was the spark plugs were worn out after running 60,000 km without replacement, causing uneven ignition and misfiring. Also, the throttle body was severely clogged with carbon deposits, leading to insufficient air intake during startup and incorrect air-fuel mixture ratio, which resulted in shaking. Aging engine mount rubber pads can cause this too—when the vibration damping fails, the engine directly transmits vibrations to the entire car. If the battery is nearly dead, unstable starting voltage can make the starter work abnormally, causing the car to shudder. I suggest you check the trouble codes immediately—don’t wait until the shaking leads to bigger issues. Small problems can turn into major repairs if neglected, and that’d be a huge loss.
