What Causes a Car to Shake at Low Speeds?
3 Answers
Reasons for a car shaking at low speeds: 1. Increased carbon deposits in the throttle, intake tract, valves, and other components: When the car is stationary, the throttle and other parts may accumulate some fuel. Upon ignition, this fuel evaporates, causing an overly rich air-fuel mixture during engine idling, which leads to unstable hot idle. 2. Unbalanced hydraulic power unit: If the hydraulic power unit fails to maintain balance during operation, the car may shake at low speeds. Simply put, this is due to insufficient fuel injection from the engine.
When driving, the car keeps jerking and shaking at low speeds, which is really unsettling. This issue is most likely caused by the ignition system. If the spark plugs haven't been replaced after 70,000 to 80,000 kilometers, the electrode gap becomes too large, and the ignition can't keep up. Another possibility is a cracked ignition coil or poor electrical contact, causing a cylinder to misfire and making the engine shake violently. If the throttle body is completely clogged with carbon deposits, the air intake is insufficient, and no matter how much the computer adjusts the fuel injection, it won't help. During my last maintenance, I found that the air filter hadn't been replaced for two years—it was almost clogged like a rag. After replacing it, the car ran smoothly again, and the idle stopped shaking. Insufficient fuel pump pressure is also a hidden danger, especially when accelerating sharply, the shaking becomes more noticeable. I recommend going to a repair shop first to read the fault codes and prioritize fixing the spark plugs and throttle body.
The last time I experienced low-speed shaking was when starting from a traffic light, and the entire steering wheel was vibrating. The mechanic said there are three common causes: fuel system issues are the most typical, such as injectors clogged by impurities from low-quality gasoline leading to poor fuel atomization, or a fuel filter that hasn't been changed for too long causing inadequate fuel supply; ignition system failures are also common, where worn-out spark plugs or aging ignition coils can cause misfires; and mechanical problems like cracked or aged rubber mounts in the engine mounts, which directly transmit engine vibrations into the cabin. In my case, it was the cracked engine mount rubber, and after spending a few hundred to replace it, the car was immediately stable. Additionally, for automatic transmission cars, it's important to check the transmission fluid and torque converter, while manual transmission cars should have the clutch plates inspected for uneven wear. For a simple check, you can try starting the engine cold and shifting into neutral—if it shakes at idle, it's likely an engine issue; if it shakes while driving, it might be a chassis or drivetrain component problem.
