I have a 2000 Audi A6 with a 2.8 motor and it's making a weird humming/buzzing noise when accelerating. There is no noise when the car is running and standing still. It only does it when I'm accelerating and trying to pick up speed. Any ideas on what it could be? Please help.

 

where does the noise seem to be coming from? is it an engine noise? is it a wheel noise? is it an exhaust noise? do you hear the noise if you are sitting still and revving the engine, or only when moving. maybe your car doesn't know the words so it is just humming.

best guess is tires. check your pressures. make sure they all match. check tread wear.

good luck

 

If the noise you're speaking of sounds like a muffled buzz or metallic rattle and is only heard while acclerating or when the car is under load, you may have something loose on your exhaust system. Check for a loose exhaust band clamp or a loose or broken weld on any portion of the exhaust heat shield around the Catalytic converters, resonators, or mufflers.

 

It looks like the noise is comming from the engine, but it's hard to tell. Most of the buzzing noise seems to be when I'm trying to accelarate. The weir parts is that once I reach a certain speed and I continue to drive at that speed the car doesn't make any noise.

 

have you investigated this? there is increased pressure in the exhaust system when the engine is working under load (during acceleration). The pressure is less once you get up to speed. it could explain what you describe.

 

I looked at my exhaust today and it looks like my exhaust flex pipes have a few small holes in them and I think I'll have to replace those soon. Could that be my problem?