[Biturbos4] strange engine sound

[Nicholas Mistry]

Last night, while driving about 20 mph, a strange sound was emitted from the engine cavity of my 2001.5 S4.   (stock, 54k miles).    I can only describe it as a loud and deep pop,  followed by a rather loud woosh.    From the drivers seat, i localized it to somewhere beyond the footwell on the passenger side of the car .   The sound was loud enough that everyone in the car could hear it clearly.   All gauges were normal, no warning indicators, car seems to drive fine.    Initial visual inspection did not reveal any indication of what happened.   Hoses/belts were intact.  Inspected all 4 tires, they seem normal.   No signs of any type of fluid leak.    Looked in the wheel well, everything was fine.     Brakes functioning normally.

This afternoon, i plan to do a more thorough visual inspection and plug my car into vag/com to confirm that my turbos are still building pressure.  

Any ideas as to what would cause this?   

-N

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Nicholas Mistry
nick at mistry.com