[BiturboS4] Blown turbos

Walter J Green Jr vr6pilot at hotmail.com
Wed Sep 4 15:28:30 EDT 2002

awesome response-post dave. nice work.


>From: "Edwards, Dave" <Dave_Edwards at iOra.com>
>To: "'biturbos4 at audifans.com'" <biturbos4 at audifans.com>
>Subject: [BiturboS4] Blown turbos
>Date: Wed, 4 Sep 2002 18:12:02 +0100
>That depends what you mean by 'blown'. Turbos which have truly failed will
>result in serious loss of power and possible engine damage if parts of them
>get into it. However much more typical is the case when damage first starts
>to happen to them. Typically this is either from general wear, lack of
>lubrication or overspin due to air leaks. The first thing you would notice
>is an increase in noise.
>On a healthy S4 you should only hear the turbos when the windows are down.
>You'll hear a feint whistle at low revs, nothing more. As soon as the boost
>comes in, the general engine/exhaust/wind noise should drown anything out.
>If you start hearing the whistle more loudly, the turbos are starting to
>die. If you hear a siren noise they are dying. If you hear any metallic
>noise they are nearly dead.
>As I mentioned, air leaks are a common cause of turbo problems. To
>illustrate this, a friend of mine recently replaced his TBB with an APR
>bipipe and found a tear in the TBB. At the same time the turbos became
>noisier (he can hear them whistle with the windows closed), and of course
>is getting a lot more power. He thinks the TBB could have been leaking
>he bought the car (used) a year ago, which is why he didn't notice it.
>Fortunately for my friend this gives him a (welcome) excuse to have K04
>turbos fitted and get a 400bhp+ car!
>And that's the main problem. You'll only notice major air leaks. For minor
>leaks, the ECU manages to keep the boost at the demanded level, but as a
>result the turbos are working harder (increased air flow - more spin). For
>more serious leaks there will be a loss of power (and often the ECU will
>detect it and go into limp mode).
>So what are the solutions?
>Firstly regular checks, but this is difficult: Some TBB leaks can only be
>found by removing it (not too difficult but a pain to do on a regular
>basis). Same with the DVs and intercooler pipes. So I recommend that you
>rid of the crap Audi parts and replace them with good. The TBB can be
>replaced with the APR bipipe (which I thoroughly recommend), and in doing
>you can check your intercooler pipes and make sure they are secure. The
>Bosch DVs are prone to leaking, so replace them with Forge or Bailey's
>(which may be slower, but reliability is more important). If you have the
>APR bipipe then the Baileys fit better than the Forge.
>Get a boost gauge. When you are familiar with what boost your car gives
>healthy, it 'may' help you see when there are problems.
>Get VAG-COM. With this you can regularly check for DTCs which 'may' help
>warn of problems.
>Use the right engine oil (fully synthetic to VAG 503.01) and change it
>Observe proper warm up and cool-down procedures (the former is more
>important than the latter).
>Hope I've been of some help,
>Message: 2
>From: "California Fields" <cfields72 at hotmail.com>
>To: biturbos4 at audifans.com
>Date: Tue, 03 Sep 2002 23:11:46 -0700
>Subject: [BiturboS4] blown turbos
>[ Converted text/html to text/plain ]
>This may sound like a dumb question, but I'm curious how one would know if
>one of the turbos is blown on the S4.  Would the lack of power be that
>obvious? Any sounds or such that would easy to detect?
>What about any leaks in the diverter valves, throttle body, or other parts?
>Carter Fields - San Francisco
>'01 santorin blue
>stock (not for long!)
>BiturboS4 mailing list
>BiturboS4 at audifans.com

'01 S4

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