boost venting

[BirdManFJ]

Hi, I have a 1.4TSi GTSport (125kw) with DSG as a recent purchase. I regularly drive to Sydney from Newcastle, and have noticed some weird behaviour when boosting up hills. At 110-120kph, the engine is doing 2.5-3k rpm (so not in turbo range yet), and when going up long hills like the Moonee bridge, it is on full boost to maintain speed. However, it won't stay at full boost. It drops to 3/4 boost for about 1 second then back on again for 3 seconds, like it's building and venting, building and venting. I took it to VW who said I had a boost leak and replaced 2 seals. This seemed to make the car run a little better, but hasn't fixed the problem on hills.
When I give it a boot at slower speeds, it will hold boost right up through to turbo and beyond. It's weird.
I also recently installed a GFB DV+ which didn't make any difference either.
Any suggestions?

[Herbi3221]

get the latest revision dv from vw. GFB DV+ has a tendency to get stuck open. is the car mapped at all?

[BirdManFJ]

get the latest revision dv from vw. GFB DV+ has a tendency to get stuck open. is the car mapped at all?

Not sure what version it had prior to replacement with GFB DV+ No tune just OEM. VW mechanic reckons it might be SC clutch slipping

[Umai Naa!!]

Fit a proper boost gauge, and re-test.

The one on the dash is simulated, for want of a better word.