Why does the engine idle smoothly but still shake?
3 Answers
Hill Start Assist is a default-enabled function that cannot be turned off. Below are some details about Hill Start Assist: 1. This feature usually doesn't have a dedicated button. When stopped on a slope with the gear in drive position and the brake pedal released, Hill Start Assist will automatically activate. In some vehicles, the function activates when the brake pedal is pressed. The braking duration lasts only a few seconds - if throttle isn't applied in time, there's risk of rolling back. 2. The Hill Start Assist system is typically integrated with the Electronic Stability Program (ESP). If the vehicle's ESP remains enabled, the Hill Start Assist function will also stay enabled by default.
When repairing cars, I often encounter situations where the engine idles steadily but the car body shakes. Possible causes include aging engine mounts, where the worn rubber components can no longer dampen vibrations; or faults in the ignition system such as spark plugs or high-voltage coils, leading to misfiring in a cylinder. Fuel system issues should not be overlooked either, as clogged fuel injectors can cause uneven fuel distribution. Excessive carbon buildup is also a factor, with carbon particles accumulated from prolonged idling leading to incomplete combustion. It's best to check for any loose components under the hood and measure the RPM fluctuations during idle. If you can't handle it yourself, promptly visit a professional repair shop for diagnosis to prevent the issue from escalating into a bigger problem.
My car has been experiencing the same issue recently. The idle RPM is stable, but I can feel the seat shaking when sitting inside. A friend suggested it might be due to a dirty air filter affecting the air intake, or old spark plugs causing poor ignition. An imbalanced engine could also result from a malfunctioning fuel pump or poor fuel quality. Additionally, worn-out engine mounts can transmit vibrations to the car body. It's recommended to start with simple maintenance, like replacing the air filter and spark plugs. If that doesn't help, then check the fuel pump and mounts. Don't underestimate this shaking—it can lead to driver fatigue and damage components over time. Addressing it promptly is always the right move.
