Vacuum Control Solenoid Valve System?

[Concorde]

Hi,
could someone tell me what could be wrong? I have CEL #71 on the dash. Does it mean all the vacuum system in general or is it boost solenoid or something like that? I also have TCL #77 which is TCL vacuum system. Is there any coherence? I visualy checked all the houses and they seem fine. I also tested the two solenoids on the firewall and they held pressure without any issues. That little grey vacuum tank is also in good condition...

 

[MrMann]

Hate to revive a dead thread, did you solve your issue?
Also, can anyone chime in with where to start looking for the fault?
When the error does come up on the dashboard, I can hear a small hiss coming from the passenger side of the engine bay.
I'll start by taking out the intake hoses and looking under there. Fingers crossed this issue might also solve my boost issue.

 

[MrMann]

So I found part of the problem, my BOV is so low to the ground it just scrapped a hole into it over time. Anyone made a guide on moving the BOV yet?
Luckily I had a replacement on hand so no worries.
But now my hiss has moved towards the intake manifold/rear turbo.
So I attacked it with the soapy water and couldn't find the hiss. Not gonna lie it's driving me bonkers hearing the problem and not finding it. I'll give her a couple more goes, and take out more of the intake piping/box before I call it quits and take her to a professional to find the hiss.
The more I'm under the hood, the more I understand why it's so expensive to get work done under there.