Audi A6 2.5 TDI: Air Vent Noise Problem?

Hello,

Subject: Audi A6 2.5 TDI V6 Tiptronic, manufactured in April 1998.

'Can anyone tell me where this air leak noise is coming from when I accelerate? When I floor it from low RPMs, it starts to hiss slightly around 1600 RPM, which gets progressively louder and ends with a slight jerk and loss of power at approximately 2200 RPM. When I test with VAG-COM, the boost pressure seems okay, but somehow... The turbo doesn't have a wastegate, so it regulates boost using a VTG (Variable Turbine Geometry) system. I'm not sure where this noise is coming from.'

Hello,

Please check the boost pipes from the turbocharger to the intake manifold for any leaks.
What does the error memory contain?
(have you already checked the error database?)

Hello,

The error memory is clear, and the pipes have been checked.

Peter.

Hello,

Could you please provide the values that you obtained using VAG-Com?

Take a look at the lower control arm (LLK), especially from underneath, and pay attention to any oily spots. Even small holes in the LLK can have serious consequences – your description is very similar to the defect I had, which was caused by a relatively small hole that made similar noises and also produced soot.

Take a look at the pictures: http://www.informatik.hu-berlin.de/~richling/tdi/

"Sorry for the poor quality; I didn't have my digital camera back then. If you're interested, I can take some new pictures sometime in the next few weeks, as the LLK is still around."

Best regards,

Jan.