(apologies if this has somehow posted twice, google chrome fail!)

Hi all,

I've got a weird sound under acceleration and wondered if anyone knows what it might be.

I have an Audi A3 1.8SE, 2000/01, non-turbo. Bought it a couple of years ago, and it's got about 85k on the clock. Has a new cambelt and new exhaust.

When I first bought the car, I noticed a faint whilstling/airy sound whilst accelerating, no garage could identify a fault so I let it be.

Couple of weeks ago, the catalytic converter failed (horrible rattling/clunking noises) so the garage replaced the entire front section of the exhaust for me (with the middle and rear sections having been replaced last year).

I immediately noticed that the weird sound was now massively pronounced. Whenever I accelerate there's a very weird airy/raspy/breathy/whooshing sort of noise. Sounds a bit like the noise a garden hose makes when you're watering your plants.

It immediately kicks n on acceleration, and immediately disappears when I lift off the accelerator. Its absent at cruising (whatever the RPM may be) and the noise is exactly the same whether I begin accelerating at 2,000 or 4,000 RPM. When I downshift, sometimes there's a quieter popping sound, in the same tone.

Garage said that its probably because the cat is new and needs to get worn in, and to leave it two weeks and bring it back if it doesn't go, and they'll replace under warranty, although I'm not convinced.

Having looked under the car, the noise seems to be coming from a small part just infront of the cat, it's a round sections that looks like a sort of metal pineapple, if that makes sense.

If anyone's got any ideas, I'll be glad to hear them.

Thanks.

 

If that 'pineapple' looks like the pic below, that is called a flex section. You said it's brand new though. It might have been damaged anyway, who knows.
It would be pushing air out through any tiny holes or cracks, and the smaller the hole/crack the higher pitched the noise/whistle.