What are the reasons for engine idling vibration that stops after accelerating?
3 Answers
When a car's engine vibrates at idle but stops vibrating after accelerating, the common reasons are as follows: 1. Severe carbon deposits inside the engine: Carbon buildup on the throttle body, fuel injectors, spark plugs, and pistons can absorb combustion heat when accumulated to a certain extent, leading to knocking or detonation. 2. Ignition system issues: Excessive carbon deposits on spark plugs or insufficient ignition voltage can cause misfiring in one or multiple cylinders, resulting in insufficient engine power and vibration. 3. Unstable fuel pressure: The fuel system includes components such as the fuel tank, fuel filter, fuel pump, oil-gas separator, fuel lines, and fuel gauge. Any issue with these components can lead to unstable fuel pressure. 4. Aging of internal engine components: This situation typically occurs after the vehicle has been used for a certain number of years or mileage. Severe reduction in engine power can cause vibration, and such vehicles are prone to shaking at low RPMs, with symptoms improving slightly after accelerating.
My old car used to have idling vibration issues, and looking back, it was really annoying. Idling is when the engine runs at low speed, and the problem might be due to severe carbon buildup in the throttle body. Too much grime can block the air intake, reducing airflow and causing a lean air-fuel mixture that burns unevenly, leading to strong vibrations. When you accelerate, the increased RPM helps flush out the dirt, restoring normal airflow and stopping the shaking. Another possible cause is carbon deposits in the fuel injectors affecting fuel delivery. Additionally, worn-out spark plugs might misfire at low speeds but work fine once warmed up after acceleration. My car was completely fixed after cleaning the throttle body and fuel injectors. I recommend getting it checked at a repair shop early—don’t delay, as prolonged issues can spike fuel consumption and damage the engine. Adding fuel additives occasionally while driving can also help prevent minor problems.
I don't have extensive driving experience, but I've encountered several instances where the car idled roughly but smoothed out after pressing the accelerator. It feels like incomplete combustion during low-speed idling, possibly due to a dirty air filter or minor air leaks causing sealing issues. At idle, the engine's low air intake makes these problems more apparent, but pressing the accelerator increases airflow, masking the issue. Additionally, slight clogging in the fuel system, like the injectors, can cause insufficient fuel supply and shaking at idle, while running normally at higher speeds. After replacing the air filter myself, the situation improved significantly. It's important to pay attention to cold-start performance; if the shaking persists after warming up, it's best to get it checked to avoid major issues. Safety comes first—don't overlook these small details to save trouble.
