KtrainHurricane

I just picked up my 2001 S4. It has 52,xxx original miles on it, and the turbos were recently replaced (within 2k miles) with "perfectly working used units off another car that had 10k-11k," per the mechanic. The mechanic wrote up a document stating this as well, so I believe that the work was done.

I have never been in an Audi before in my life, let alone an S4/other turbo model...and I am not sure if the sound I am hearing is whine from the turbos, or what I've also been told it's referred to as the "dentist drill."

I noticed the sound when driving in city traffic, from stoplight to stoplight. It sounds like a slight "whine" and seems to follow the boost - meaning that if the RPMs go up the sound does not; if the boost goes up the sound gets higher + quicker and will stay at a steady tone if the boost is at a steady PSI. Once I get on the highway or at "crusing speed" (at or above 50 mph or so) I can no longer hear the noise. I do not know if it is because road noise is louder or because the "whine" stops. I may be crazy and this may just be the sound that the car makes normally, but of course I am very paranoid since I just bought the car. Any and all help is appreciated, thanks!

Stones399

First, has the car had any mod's done to it? Or is it factory?

If you've never driven a turbo car, you may not be used to hearing the turbo "spool up". Especially if has been modified to allow a more free flow. But if it's excessively loud, you may have bad turbo(s). The blow-off is more of a chirping noise.

I had my turbo blow 2k miles after I picked it up from the dealer. Thankfully it was covered under the warranty. But mine were really loud and there was a pronounced drop in power. I don't have a boost gauge so I could help you as to where the boost read, but it had to be down because of power loss. Do you feel a power loss? That would be a key to bad turbo.

KtrainHurricane

The car has a GIAC chip, which is what the mechanic said is to blame for the original turbos blowing. However, the "new" turbos were put in around 800 miles ago or so, and the car has NOT been driven hard since then. The mechanic was just driving it to the store, gas station, etc. and back to his shop to keep the parts in the car moving. When I test drove the car, I got on it 1 time but was only WOT for about 5 seconds or less (was just checking to make sure the car pulled as it should). The mechanic said I was the 1st and only person to come see the car. It also has an aftermarket intake, and the mechanic said the car "may" have downpipes, but he did not remember for sure to give his word on it.

I have had/been in my share of turbo cars. I have personally owned two Buick Grand Nationals and a big turbo Nissan 240sx SR20det, all within the past 3 years or so. It may be because I have never had a twin-turbo car or a car with such small turbos, but the sound I hear is nothing like the turbo spool I have heard in the past.

I do not feel a power loss so-to-say, but again - I have never owned one of these cars before. The boost gauge climbs steadily as it should and the car feels like it is making nice power...but I have nothing to compare it to.

My radio is in "Safe" mode so I have been enjoying every little tone the car makes. I drove it some more this afternoon, and when I put the windows down the sound was similar to that of a whistle more than a whine. Once I rolled the windows back up, though, it was back to whine...

hodan

There are tons of youtube videos of "dentist drill" turbos. Just compare the sound.

Healthy S4 turbos whistle, if you get an aftermarket exhaust, cold air intake, downpipes or piggie them, the whistle gets louder.

I think most people that have owned an S thought their turbos were bad, lol. I did and they weren't.

Oh, and btw, there are NO BLOW-OFF valves in an S4. The turbos don't sound the same, generally, as other turbo'd cars.

KtrainHurricane

Well, I can say that:

My car kinda DOES sound like this: http://www.youtube.com/watch?v=iKnI3DS8ino

But it definately does NOT sound like this: http://www.youtube.com/watch?v=XSEFU...eature=related

I also DO have an aftermarket intake, and as previously mentioned the mechanic said that I "may" have downpipes but he did not remember for sure to give his word on it...