Noise after cold start
 

2009 A4 Avant 2.0T, bought in March 09. After cold start (after sitting in garage overnight, even if 70F+ ambient temp), I hear a noise that sounds like the muffled roar of jet engine. Comes from front passenger side engine compartment. Lasts about 40 seconds. Dealer service dept diagnosed source as secondary air pump, but when they went to get part number off it, they said I don't have one. They want to keep the car for a couple of days and 'talk with Audi.' Anyone else experience this?

Has always done this. I figured it was a characteristic of the new engine, but after listening to others on the dealer lot, realize this isn't normal.

Sure its not the Aux fan kicking in?

I also hear a odd noise when I start my 2010 A4 CVT. I only hear it in my garage in the morning. I have several theories: 1) it's the CVT warming up, 2) the CVT makes that noise all the time but I only hear it in the garage because it amplifies sounds, 3) something is actually wrong with the car? I don't hear it at night when I come home from work, so I believe it has something to do with cold starting. Does anyone else hear this? Do you hear it with Quattros or is it just with the CVT?

Yep, jet-engine noise here too
 

Whew! I thought I was the only one 'taxing for take off' everytime I start my car. It is especially noticable in the garage and it is exactly as you both describe.
I have 2009 2.0T Quattro with auto and I defintely have the jet-engine noise at start up.

That was one of the first worries I had with my car as well. I spoke with a couple Audi service advisors and they both said it is the air pump for the pollution control.

i am also getting that "jet engine" sound at cold start ups...I hate it. So...are they saying that there is a fix?

Based on 'poppy's' reply (thanks for that input) the service advisors seem to consider it normal at start up.
I am no expert here but maybe the pollution control air pump goes into overdrive at cold start up to reduce emissions since the engine is not at full operating temperature????

working temerature on A4
 

Audi A4 1.9 tdi 2000 years 85kw 116hp. After much mileage lift working temperature of 92 degrees in normal whether condition of 7-10 Celsius.

Looks like Audi has put out a service bulletin on this stating that the roaring sound is a normal cold start characteristic of the new 2.0 engine.

Audi noise with sound file
 

Is this the noise you guys are hearing?

I have a 2010 A4 Avant and THOUGHT there had been a lot more airline traffic recently.

Service center kept overnight, but it didn't reproduce for them (of course).

Will hear hood open and I moved the recorder around to the right front (passenger side) to where it was loudest while the recorder was going

http://dl.dropbox.com/u/256070/AudiSound.wmv