Hi,

So my car just got an engine swap, since old one lost compression. Prior to that "event", it was working fine. Got a used engine with low miles, so out with the old, in with the new.
However, after reassembly, the car runs, it drives fine, but it has secondary turbo boost issues. When I drive up to 4500 rpms, I get full 0.8-0.9 bars of boost - but when I go past that, boost drops down to 0.4-0.5 bars. Also when I left off the throttle, boost continues to be only up to about 0.3 bars - even at 4k rpms - to fix that, I need to go below 3000rpm, to kinda "deactivate" secondary turbo, to get back to good working boost.
I'm not suspecting any hardware issues since the car run perfectly fine with old engine, so I guess it's very likely some vacuum lines just got misassembled?

After reading some forum posts, I naturally went down to Y-pipe and checked how was it connected. This is the picture of three lines and how are they currently connected:


Is that correctly connected?
I'm not really sure because it's really hard to find pictures of this place, for example I've found an image like this one:

As you can see, three exposed vacum hard lines, good, but it doesn't match what I actually have on my car, this "top" one is too far upwards. Also, there is one more thing:

What is this short one for? It's currently empty, it's very far upwards, just at the meeting line between lower and upped intake manifold.

I'll really appreciate any help, it's double hard to figure out because I have JDM 99 model and it's slightly different than normal US/Euro ones. If more pictures are needed, I'll be happy to provide. I also have a video of a boost gauge demonstrating this boost problem

 

That sounds more like a problem with the turbo control actuator. I'd focus on that first.

I know someone has posted the 96+ vacuum line diagram, do some digging, it's around somewhere.

Dale