General: Engine 2.0D - Boost issue / ECM 2263

[TheGrinch]

Hi,

I may need your help,
I have intermettently the fault code 2263 with the following symptoms : With little / medium throttle, the boost build up, then suddently hardly cut, then build up.
Sometimes, the fault code doesn't appear but have the symptoms.
No limp mode.

the investigation I have made :
- replacement of the Turbo Control Valve with a pierburg one.
- I have vacuum at the enter of the TCV
- I have vacuum at the exit of the TCV (so to the turbo vane)
- I have monitored various trip with vida :

I have seen that the TCV position at idle is stick to 99%, and stay at 99% all the time when riding, except when the turbo boost "cut". It's like there is no smooth regulation, it's like just an on/off on the TCV.
The boost "cut" occur when the MAP reading is higher than the "desired boost value", but still in acceptable value (lower than 2300 Hpa), which seems to be normal.

- I have check the voltage on the TCV plug at idle, which is 14V, which correspond to the 99% open from VIDA.


My questions are :
- What is the normal value of the TCV position at idle ?
- The TCV position should change all the time, right ?
- Could be a sticky boost vane ?

Thank for your help !