# 2002 S4 2.7t Weird Problem.. One turbo cuts out at operating temp..



## xxipsxx (Dec 11, 2010)

Really not sure what to think. At first I just figured that one the the turbo's is on its way out, but the more and more I drive it I tend to think that this isn't the case. I haven't had time to put it on the lift and check it out, but here is what it is doing....

When I first start the car I have a nice clean start up no unusual noises, no rough idle, no smoke(white/black). While the car is cold it runs perfectly, boosts 9-10psi (stock tuning). When the car reaches operating temperature this is where things get fuzzy. The boost reduces to 5psi and in lower gears with low road/engine noise I can "sometimes" hear a flutter coming from one of the turbos I think. I have 2 codes that have been up for a long time, one is for an evap vent and the other is for a rear o2 on bank 2. The car ran fine for months with those codes up so I don't think this has anything to do with what is going on but I figured I'd just throw it out there.

I'm now starting to think that maybe its a wastegate/n-75 valve issue? But I could have been right in my first assumption that the turbo is just on its way out and it makes a nice seal until intake temps get high enough to heat up the damaged seal and and loose its viability.

Tell me what you think? I won't call you an idiot for trying to help so please....


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## EazEonMahJetta (Sep 2, 2002)

Just an idea... have you checked for boost leaks under load? Granted, it does sound like you're hearing the turbo try to fight air... which would lean towards wastegate issue... just tryin to think outside the complicated box and K.I.S.S.


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## Jurjen (Oct 9, 2002)

EazEonMahJetta said:


> Just an idea... have you checked for boost leaks under load? Granted, it does sound like you're hearing the turbo try to fight air... which would lean towards wastegate issue... just tryin to think outside the complicated box and K.I.S.S.


This.


Check for boost leaks  Rule the simple **** out 1st.


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