What Causes the Engine to Buzz When Accelerating?
2 Answers
The reasons for engine buzzing when accelerating: 1. Exhaust pipe leakage: When there is a leak in the intake or exhaust pipe, the vehicle will produce a loud roaring sound as the exhaust rate increases during acceleration; 2. Dirty throttle valve: During acceleration, the engine load increases, requiring a higher throttle opening. If the throttle opening is not optimal due to dirt blockage, it can lead to poor air-fuel mixture ratio, resulting in noise during acceleration; 3. Engine misfire: An engine misfire refers to one or more cylinders not functioning properly, typically manifesting as insufficient vehicle power, severe exhaust pipe shaking, and clearly audible "popping" or thumping sounds from the engine.
I've been driving for twenty years and have heard this kind of humming sound way too many times. When you step on the gas and it sounds like a beehive, it's most likely a failing pulley bearing. If the belts in the engine bay are old or cracked, or if the water pump or alternator bearings are worn, the noise becomes especially noticeable when accelerating. Just the other day, I helped my neighbor diagnose this issue—turned out his alternator bearing had disintegrated, and replacing the entire unit made it quiet again. Another possibility is an exhaust leak; try crouching near the rear of the car when it's cold-started to see if you smell exhaust fumes. Honestly, the safest bet is to take it straight to the repair shop and have them check it on a lift. If the axle boot rubber dust cover is torn, that needs immediate attention too.
