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Discussion Starter #1
Guys, a whole bunch of people now are trying to sort out my problem....any ideas are very welcome

The problem is the following:

The car overboosts for some reason and then offloads the pressure or whatever the correct word for that is...you can hear it as you go. For example going on 3rd gear with 1800rpm and then you suddenly floor it....it starts to build up pressure then at 2100rpm it goes psssst (bit like a blow-off valve)....and then builds up pressure again until lets say 2400rpm, and loses pressure again...it only makes it (well noticeable) between 1900 and 3000rpm...when you're driving it it feels like multiple surges...
I must have a log somewhere but it generally loses around 300mbar....

No error codes
things done so far:
tried new MAp
tried new n75 valve
tried new vnt actuator (The thing that looks like a wastegate)
cleaned variable geometry vanes
changed maf
re-mapped the car incl. almost completely eliminating the n75 valve's sensitivity...
checked vacuum lines and pump


all gave little or no improvement....

Any ideas are welcome....
 

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Check the intercooler for splits or holes would be my guess if you can hear a venting noise (that is if you've already checked the turbo and intercooler hoses?)

Friend of mine had similar issues with his Audi A4 and eventually found the intercooler split on one of it's cores.

No mention of the EGR, have tried running with it disconnected (just for testing purposes)?
 

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Discussion Starter #3
yes we have tried to shut the EGR down with one of the maps...
And I also took out the cooler for a cleanup and it wasn't leaking water from anywhere...
Turbo hoses seem fine...if it was a hole somewhere it would just lose pressure from there continiously, not loose it for a moment and then not i think...it sounds like the boost comes out of a valve or something similar...
 

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Hook up a laptop and make logs of:
- rpm
-actual boost
- vnt%
- airflow

And post them here.
 
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