What causes the engine to make a humming noise and accelerate slowly when stepping on the throttle?

[LenaLynn]

The reasons for the engine making a humming noise and accelerating slowly when stepping on the throttle are as follows: 1. Engine fuel pump issue: A damaged engine fuel pump leads to insufficient fuel supply. Even if the driver floors the throttle, the engine RPM increases, but the fuel injection volume remains low, resulting in reduced engine power output and naturally causing sluggish acceleration. 2. Valve timing issue: To improve fuel efficiency, modern engines use CVVD valve timing systems. However, if the CVVD hydraulic control system is damaged, the sealing ring leaks oil, or the CVVT malfunctions, the engine's intake and exhaust processes are affected, naturally reducing combustion efficiency and diminishing the engine's torque output.

[RafaelLynn]

As a veteran driver with over 20 years of experience, I've encountered this situation multiple times. When stepping on the accelerator, the engine makes a buzzing sound while the speed fails to increase, making the car feel like it's struggling to climb a slope. The most common culprit is a clogged air filter preventing proper airflow into the engine, leading to incomplete fuel combustion; or a faulty fuel pump failing to deliver sufficient fuel, causing both the buzzing noise and sluggish acceleration. Another possibility is ignition system failure, either from carbon buildup on spark plugs or aging coils. The buzzing could also indicate an exhaust system leak, such as a crack in the muffler. Don't underestimate this issue - prolonged neglect not only wastes fuel but may lead to dangerous roadside stalls. During routine maintenance, remember to regularly replace the air filter and inspect the fuel system, with carbon cleaning typically recommended every 10,000 kilometers. Last time I fixed the problem simply by replacing the air filter, so I recommend visiting a reliable repair shop promptly before serious damage occurs.

[Harmony]

From experience, when an engine produces a humming noise upon acceleration and exhibits slow speed increase, it often involves several key components. A dirty air filter restricts airflow; a malfunctioning fuel pump or clogged fuel injector leads to insufficient fuel supply; aging ignition coils or spark plugs reduce ignition efficiency; and exhaust system leaks or excessive backpressure cause noise and sluggish acceleration. The humming sound may also result from resonance due to damaged engine mounts. These issues can lead to delayed acceleration, increased fuel consumption, and safety risks. Simple DIY checks are recommended: first inspect the air filter and replace it if dusty; then check fuel line pressure. For prevention, avoid frequent hard acceleration or prolonged idling. If the humming is accompanied by vibrations, stop driving immediately and seek professional diagnosis—avoid DIY attempts that may worsen the situation.

[JamesRose]

My car had this issue too - a buzzing sound when stepping on the gas, with acceleration slower than a snail. Common causes include a clogged air filter (replacing it might help), or an aging fuel pump causing insufficient fuel supply and weak engine performance. Cracks in the exhaust system can also create noise. Slow acceleration might stem from excessive carbon buildup - cleaning the throttle body often helps. Don't ignore the buzzing; it's your car protesting and needs prompt attention. Get it checked at a repair shop - the cost is low compared to risking a roadside breakdown. For daily driving, avoid frequent short trips with constant stop-and-go to minimize such problems.