What Causes Car Idle Shaking?

[McVera]

Car idle shaking is caused by: 1. Severe engine carbon buildup; 2. Dirty throttle body or excessive injector carbon deposits; 3. Faulty spark plugs, high-voltage wires, or ignition coils leading to poor ignition system performance; 4. Unstable fuel pressure, insufficient fuel pump supply pressure, or incorrect intake pressure sensor readings; 5. Fuel line blockage causing insufficient fuel supply; 6. Aging engine components. Solutions for car idle shaking: 1. Clean engine and idle motor carbon deposits; 2. Clean fuel lines; 3. Replace spark plugs, high-voltage wires, and ignition coils; 4. Clean air filter and throttle body; 5. Replace aging engine components.

[CarolineLee]

I've been driving for over a decade, and idle shaking is quite common. It's mainly caused by thick carbon deposits inside the engine affecting smooth combustion, making the car unsteady when parked. If the spark plugs are worn out and the ignition is unstable, it can also cause this. Insufficient fuel supply, such as clogged fuel injectors, can lead to shaking as well. If left unattended for a long time, carbon deposits can worsen engine wear, affect performance, and even reduce lifespan. I recommend regular carbon cleaning and checking the air filter and spark plugs every six months to prevent shaking and ensure safer and smoother driving. By the way, a dirty air filter causing poor airflow can also easily lead to shaking, and simply replacing it isn't too troublesome.

[SanRonan]

My old car used to shake badly at idle, even at red lights I could feel the seat vibrating. Turned out the engine mounts were loose, and reinforcing them stabilized it. Worn-out spark plugs causing weak ignition can also lead to shaking, and fuel system issues like a failing fuel pump causing insufficient fuel supply similarly result in instability. If not addressed promptly, the engine may experience premature wear, and fuel consumption could increase. At home, I regularly check if the spark plugs need replacement or go to the shop for a simple diagnosis—spending a little money ensures worry-free driving. If the intake is clogged, just cleaning the air filter will do; these are minor issues that don’t affect daily driving.

[LaGabriel]

Idle shaking is mostly due to spark plugs needing replacement. If the engine fails to ignite, the car will naturally shake. It's quite easy to replace a new spark plug yourself. Another common issue is a clogged intake tract causing insufficient air intake, or the fuel pump failing to supply enough fuel. If frequent shaking is left unrepaired, it may damage engine components. It's better to visit a repair shop early for inspection to avoid wasting time and money. Regular maintenance of the air filter can also reduce shaking.