Hello,
as I said in the introducing section, I´m a brand new FL2 owner.
After driving the car a few days, i recognize an odd sound when I accelerate the car in 1st.
I guess I didn't notice it at the beginning , but it could have been there all the time.
It has an auto gearbox, this information might be helpful.
After searching for odd, whooshing noises, the only thing I found was about split hoses in the turbo/intercooler area. But as I understood, this will come together with lack of power, but I think this is not given at my car - I was driving on the autobahn, short speed test included, and the car did it very well.
I made a short video where it is hearable. After a sec I stop the car and accelarate, then you can hear the huhuhuuuu-whoosh sound. It's only noticeable in 1st, checked that more than twice.
Is it something strange or is it normal? Maybe here's somebody around who can tell me.

It sounds like it's only doing it in 1st, so it's most likely to be something gearbox related. However under acceleration in first, the Haldex feeds some power to the rear wheels. This noise could be the start of the rear differential bearings failing, which is very common, and can be rather alarming, if they seize, like mine did at the weekend.

personally i would still check the intercooler hose coming from the throttle body, make sure the jubilee clips are tight, and there is no tiny split, then check intercooler hose from under the car to turbo. Sometimes there can be a split or clip loose without losing power, another place to look in air intake pipe.
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@Arctic2
Thanks for the advice, I´m going to check that. I saw that silicone hoses for this use are offered, are they the best replacement?

It could be the turbocharger waste gate

@freelance thx for your answer.
If so, shouldn't the sound be hearable in the higher gears, too?

Sd 4 I had only ever made the noise in 2nd gear, which it usually pulled away in