After suffering from regularly limp mode and then always limp mode/lack of power, I did the Mr. Muscle clean up of the VGT-housing and cleaned the inlet manifold. I found that the constantly lack of power was a hole in the vacuum line to the actuator. I fixed it and I had boost pressure again without limp mode. Turbo didn't make any particular sound other than the faint spooling heard when driving along walls. But now there is no spool sound to be heard, and the engine is lacking power.

 

I checked the vacuum line from the N75-solenoid and only the slightest vacuum moves the actuator and lever. I checked the error code and there was a "P1550 Charge pressure, control deviation code". I deleted it and did a test drive, still lack of power and no spool sound from the turbo. The code didn't come back.

So either my turbo has seized or the N75-solenoid is not working?

http://wiki.ross-tech.com/wiki/index.php/17958/P1550/005456

45 minutes ago, RallyeSport said:

But now there is no spool sound to be heard, and the engine is lacking power.

Black smoke? I'm wondering about a boost leak.

No smoke, turbo was working fine after the vacuum leak fix and Mr. Muscle cleaning. Turbo definitely doesn't spool since the spool up sound is gone.

I will try to swap the N75 for N-18 EGR solenoid, hoses and connector, to check if there is a problem with the N75, next is to see if turbo is seized.

Turbo spinned freely on inspection, so switched the EGR N18 solenoid for the N75 solenid and the turbo spool up was immediately audible on start up of the engine and engine pulled much better. Probably the N75 valve got damaged by sucking on an open vacuum line from the actuator and filled with unfiltered particles and died soon after the leak was fixed.