The infamous 17705.

[MoshiMoshi]

I'm fed up of it now. 17705 and 17545 have been stored on the car for a months now, and they have recently started tripping the CEL again. I've replaced most of the PCV pipes up to the PCV valve and oil block breather. None of my turbo pipes have spilts that I can see, and the boost has been holding more or less steady. However, I think it might be my DV as in 2nd gear, just fluttering around the 2800rpm mark i get boost spikes, that quickly "fall off". If that makes any sense.

This fault code is slowly killing me inside. Any advice?

[Wazzzer]

Boost spike sounds more like actuator to me

[jamie1989]

Try putting more pre-load on the actuator. The spring may be getting weak.

[Wazzzer]

not to say you haven't got a boost leak as well though. Bear in mind the AUM will up the boost a bit at the turbo to get you the desired amount at the MAP sensor so effectively you won't notice a small boost leak

[Nino]

Hey Pal, I too had this problem and I too did what you did. In the end I found that I needed to clean the TB & MAF 

[MoshiMoshi]

Cleaned the TB and just bought myself a new green gasket. A whopping £2.60 from my local VW garage in Melksham. It was pretty clean aside from a light coating of oil - is this normal?

The only other one to check aside from the DV is the MAF, how can I test it?

[Nino]

Cleaned the TB and just bought myself a new green gasket. A whopping £2.60 from my local VW garage in Melksham. It was pretty clean aside from a light coating of oil - is this normal?

The only other one to check aside from the DV is the MAF, how can I test it?

To test the MAF unplug it and then start the engine, if it runs better you got a faulty MAF I took my MAF off and cleaned it using Electronic cleaning spray, watch this video you will be supprized...
http://www.youtube.com/watch?v=dwm3sYYdA6g

Alittlebit of oil in the TB is normal, when I removed mine it was caked init see this topic for tips on cleaning the TB.
http://www.golfgtiforum.co.uk/index.php?topic=87783.0

To test if your DV has failed remove the DV, press the diaphragm up, put your thumb then put your finger on the top nipple, and then release the diaphragm. There should be suction created on the top of the DV that prevents the diaphragm from returning. If there is no suction and the diahragm returns then the diaphragm is leaking and the valve should be replaced. IF the valve is good, check the VAC line leading up to the valve for any cuts or tears.