Turbo spooling?

[mootsrider]

This may be an obvious question, but I'd like to see if others have the same experience.

About 5 seconds after the engine is running, I hear what sounds like the turbos spooling up. what's happening -- are the diverter valves delaying the flow of exhaust to through the turbos? Do others have this delay on start up?

I can definitely hear them spooling down after killing the engine, but if I start up again they seem to spool down to zero before going back up.

Thanks!

[BBGT2]

I hear mine as well, esp. after I installed the Milltek DP after shutdown I can can hear them more than before, sounds like a small jet winding down after flight :D !

Oh and did I mention that when mashing the throttle you can hear them whistle and spool ALOT more :0: !


Bajo:addict:

[Tweaky]

I think you will find that is the aircon fan you can hear at start up and engine off time. If you hit the econ button to kill the aircon you wont hear it. :doh:

[BBGT2]

Originally posted by Tweaky
I think you will find that is the aircon fan you can hear at start up and engine off time. If you hit the econ button to kill the aircon you wont hear it. :doh:

Ummm,
I have opened the hood and checked that when I first heard it and NO its not the electric coolant fan motor (aircon fan).

Bajo:addict:

[Tweaky]

That is strange as mine makes the very same noise at start up and engine off, and by pressing the econ button, which turns off the air con, the noise is then no longer made. Whatever it is, it definitely isn't the turbos thats for sure :)

[gjg]

Originally posted by Tweaky


mine makes the very same noise at start up and engine off, and by pressing the econ button, which turns off the air con, the noise is then no longer made. Whatever it is, it definitely isn't the turbos thats for sure

same here - AC off, no noise ..... :vhmmm:

[BBGT2]

Tweaky,
I for one know exactly what a elec. fan motor sounds like and know what a turbo spooldown sounds like as my GT2 with straight pipes makes the same noise after shutdown. Def. not a elec. motor but to me sounds like the turbo's spooling down, reason I say that is mine were faint when I had the OE DP's and got more noticable after the Milltek DP's. :cheers:


Bajo:addict:

[JAXRS6]

I compare the sound to some sort of aircraft turbojet. Couldn't tell you whether the cause is turbos or AC, at least from the way it sounds. That's a subjective judgment.

But this isn't subjective:

1. Turn the car on with AC engaged, and the sound starts.
2. Turn off the AC, and the sound stops after a second or two.
3. Leave the AC on and the sound continues.

At least, that's what happens with my RS6 and, apparently, with several others above as well.

[BBGT2]

Jax,

I agree with your subjectiveness, all I am stating is that there is a definite diff. between turbo's spooling and a electric fan motor winding up/down. To me at least the 2 sound very different in the sound they make. Might be someone thinks the fan motor sounds like a turbo and it is actually a coolant fan motor, all I am saying is that my GT2 and my RS6 (esp. the Porsche) turbo's do spool down after shutoff which to be is odd as the spooling sound we hear is actually when both the cold and hot side are the boost mode.
I am not disagreeing in that the fan motor makes noise at startup/shutdown but the fan motor does not come on due to the A/C compr. being off in ambient temps below 36' F otherwise the engine would not reach normal operating temperature.
Mootsrider if you are still worried/curious have the tech check it out at your next visit to your friendly and all knowing Audi dealer:D .
But I can tell you that on your RO it will say "Could not recreate customer concern/problem" .:mech:

[Hy Octane]

Hmmm. Ok. Lets see here.. When you are at idle, the turbos are NOT spinning..So, if you turn off the motor and hear a spooling down sound, it can only be the aircon compressor or the twin cooling fans located in the radiator area.. Mine is the cooling fans. They will continue to run for a few seconds after I turn off the ignition before they slow down.. On a related note, after a senior tech from Audi tried to fix my boost problem, he had removed much of the intake system and when he reassembled it, I now had this whistling sound under acceleration coming from the turbos.. I thought they were failing as It had that dentist drill sound we hear about.. but actually, it was the tech who had not properly fastened the components so there was a small gap somewhere that was letting the sound out. I brought it back and another tech found and fixed it. he did say that several other cars made the same noise ..

[ott]

I get the same sound as described above and I think it sounds exactly like cooling fan.

Don't know about Audi, but for example, when you turn A/C on in 4-gen Camaro, one of it's two electric fans starts working immideatly, whatever the outside temperature is.

[mi021le]

its the a/c in my car. :rs6kiss:

[BBGT2]

Originally posted by Hy Octane
Hmmm. Ok. Lets see here.. When you are at idle, the turbos are NOT spinning..So, if you turn off the motor and hear a spooling down sound, it can only be the aircon compressor or the twin cooling fans located in the radiator area.. Mine is the cooling fans. They will continue to run for a few seconds after I turn off the ignition before they slow down.. On a related note, after a senior tech from Audi tried to fix my boost problem, he had removed much of the intake system and when he reassembled it, I now had this whistling sound under acceleration coming from the turbos.. I thought they were failing as It had that dentist drill sound we hear about.. but actually, it was the tech who had not properly fastened the components so there was a small gap somewhere that was letting the sound out. I brought it back and another tech found and fixed it. he did say that several other cars made the same noise ..

What do you mean they are not spinning??? The exhaust gases mysterioulsy just bypass the turbo vanes at idle ?????
They are not creating BOOST but they are spinning.

In your case with the noise after the tech didnt install the intake cover/ MAF's correctly you should have been getting fault codes. I had the same problem with mine but didnt hear the turbos anymore loudly then before, what you heard or should have heard was air being sucked past the MAF's.

[vs2]

Definately the A/C fan in mine as well.

Did you know there is a tiny little electric pump that cools the turbo's for awhile after shutdown.

[Qisha]

The Air Conditioning pump creates the whine. This is more or less noticeable from Car to Car but normal.

Another posible cause: within the 2003 Production some Cars show that the Battery Cable runs too close with the Speaker wires, so the Alternator whine is transfered into the Audio System. This can be fixed by a certified Dealer.

If you can hear a moderate Sound coming from the Turbos under Idle, this is definately not right. Normal: chipped Cars with higher boost will produce a stronger "whistle" under full throttle.



Did you know there is a tiny little electric pump that cools the turbo's for awhile after shutdown.

Right, this is a safety Feature allowing the lubricating Oil to circulate properly. That should prevent the lubricating Oil from "burning" within the Turbos after hard driving. Otherwise there will be premature Turbo wear and/or Turbo failure. The Pump runs for a preset Cool-Down Period, you can hear it after Engine turned off located at the Drivers Side front Fender.

[54m]

It's defo the aircon unit it even on the new a6 and on the old one.I got the same noise in mine i took mine to audi and they said it was normal in all audis.:asian:

sam

[LIRS6]

Aircon here

[Hy Octane]

Clarification.. Yes, at idle the turbos are barely spinning at about 2,000 rpm. which is
nothing you could hear if they spooled down from there since they turn at about 50,000rpm under full throttle.. Point being that unless they were in an advanced stage of failure you wouldnt hear them "spool down" when you turned off the motor..