What Causes Severe Car Shaking Like Convulsions and Significant Power Loss?

[MacGeorge]

Severe car shaking and power loss are typically caused by a dirty throttle body, excessive carbon buildup in the fuel injectors, or aging engine mounts. Below are detailed explanations of these causes: Dirty Throttle Body and Excessive Carbon Buildup in Fuel Injectors: After driving for a certain mileage, a dirty throttle body can prevent it from closing properly or cause the idle speed stepper motor to stick, both of which can result in excessively high engine idle speed. Additionally, carbon deposits generated during engine operation can lead to vehicle shaking, especially noticeable when starting the car—the engine may shake more violently than usual or even fail to start on the first attempt. Therefore, when experiencing car shaking, it's essential to inspect the throttle body and fuel injectors. If excessive dirt or carbon buildup is found, prompt cleaning is necessary. Aging Engine Mounts: Car shaking can also be related to aging engine mounts. Engine mounts act as the vibration damping system for the engine, absorbing minor vibrations during operation. If the engine mounts are faulty, these vibrations can transfer to the steering wheel and the interior of the car, causing noticeable shaking at idle. The issue is most pronounced when starting the car's electrical systems while the engine is idling.

[SamanthaFitz]

I had the same issue with my car a while ago. It would jerk and shake badly when accelerating, feeling particularly sluggish. The most common cause is worn-out spark plugs, either with excessive gap or heavy carbon buildup, leading to unstable ignition and misfiring. It could also be a faulty ignition coil, causing one cylinder to completely stop working. Insufficient fuel pump pressure can result in poor fuel delivery, especially noticeable when climbing hills. Additionally, excessive carbon buildup in the throttle body making it less responsive, or a clogged air filter restricting airflow, can make the car feel choked. If the exhaust system is blocked, like a failed catalytic converter, the trapped exhaust gases can also cause suffocation. Don't force the car to run in such conditions. First, check the simple components, and if the cause remains unclear, use a diagnostic scanner to read the trouble codes.

[MacCarson]

The car is shaking like a leaf, most likely due to a powertrain issue. The ignition system is the prime suspect—things like worn-out spark plug electrodes or aging, leaking high-voltage wires can cause the engine cylinders to work out of sync. Clogged fuel injectors with deposits can also lead to uneven fuel supply, making a cylinder with less fuel shake violently. For automatic transmissions, slipping clutch plates in the gearbox can cause severe shaking and power loss. One often-overlooked detail is worn or broken engine mounts; when the rubber cushions fail, engine vibrations transfer directly to the chassis, making the shaking feel extreme. Last time I encountered this, replacing the spark plugs didn’t fix it—turned out the fourth cylinder’s injector was completely clogged. A thorough cleaning solved the problem.

[MacQuinn]

Severe lack of power with jerking and shaking? Focus on three key areas. Insufficient fuel pump pressure can cause fuel supply interruption, resulting in gasping and shaking during hard acceleration—restarting may temporarily fix it. Cylinder misfire is most common; excessive spark plug carbon buildup or ignition coil leakage can disable a cylinder. Intake system leaks are also dangerous—like aging intake manifold gasket leaks causing incorrect air-fuel mixture ratios and violent shaking. If you smell gasoline, check for loose fuel line connections. A bad pulley bearing creates rotational imbalance that shakes the entire engine. First read OBD trouble codes to narrow it down; without equipment, listen for distinct "popping" sounds indicating a misfiring cylinder.