Haven't checked that yet. Not specifically. I did, however, check the N75 directly to see how much vacuum it was producing for the actuator, and whether the vacuum was slow in coming or going. It was fine.
My problem is when you graph the boost, it is slowly ramping up to the requested level. I was wondering if the N75 was slow in releasing the vacuum, and it is not. My vacuum gauge shows the vacuum disappears immediately (well, very quickly), and since that is the action that causes the vanes to open up for full boost, then that part of the equation is OK. Similarly, the actuator lever on the turbocharger is moving easily and rapidly when the actuator moves.
Visual inspection seems OK, but I need to find a way to check the integrity of these. If there's a leak, it isn't enough to make a loud enough sound to think it is there. But my ears might not be catching the right frequencies due to my tinitis. I think a pressure test where I put compressed air into the hose at the turbocharger discharge from the impeller is needed. I'll have to figure out how to do this.
Nope. N75 output shows this is not the problem. It's acting like a boost leak.
I've not seen evidence of this. A new replacement acts the same, and unplugging makes it even worse.
No longer part of the equation. One thing I did a few days ago was to replace the intake manifold since mine was a little occluded. Most of the blockage was in the EGR valve assembly itself, but I did both of them anyway. Somehow the pesky EGR cooler didn't make it back into the car, so there's temporary block off plates installed until I get this checked out. I also installed a test device of my own design that prevents the EGR codes from being set.
As above, not part of the equation at this time.
As previously stated, I tested this directly. I put my mighty vac on the N75 output directly and it was perfect while testing with engine running and VCDS was running the N75 output test. The actuator also holds vacuum and exercises its motion correctly. That it does it while attached to the turbocharger lever shows that the turbocharger vanes are also operating.
N18. Not part of the equation at this time. For testing, my device bypasses it.
I don't think so, you've done a comprehensive listing of all the components. I think the next step is to figure out where the boost leak is. That is the way it seems to be operating to me - a leak not quite large enough to drain all the boost, but enough to greatly slow the buildup of manifold pressure.
There could be a junction that I'm not seeing, or the new-to-me seemingly good replacement intercooler isn't as good as it seems. It is hard to tell. Another possibility is that the turbocharger's turbine section is horribly occluded by soot buildup, but my thinking right now is that if so, it isn't affecting the vane motion, but yet is so hard as to completely resist the multiple application of oven cleaner chemical cleaning operations. There's no hint of soot discharge after.
I think some soapy water on the outside, and compressed air on the inside of the post turbocharger air intake tract may be my best bet.
One last place to look that I didn't do and should have is the hard pipe between the turbocharger and intercooler. That thing might be where the clog is. Hmmm, should have tried that sooner. Maybe I just need a new hard pipe.