C15 not getting boost

With the engine off, take the inlet boot off the turbo, and check the shaft for free play. If you can wobble the shaft more than about 1/32", it's toast. ANY in and out movement and it's done too.

 

The problem I have with your situation is you cant deliver anything with no boost. So are you sure you have only 2 psi of boost or just bad gauges?

 

Sounds like a possible boost sensor itself going bad

 

So I know I'm asking a lot. Did it sound any different new turbo old turbo like the wine louder lower sharper? You need to install mechanical boost gauge and fuel pressure gauge ran up 2 in front of the windshield so you can see what those two are doing. Possibly put a bung after the turbo before the CAC and get a gauge in there to see if your CAC is plugged. You could also have bad injectors. The injectors could be dumping fuel instead of spraying fuel the correct way and in, the fuel isn't burning right. There really is a pile of problems that it could be but you've got to start eliminating some thing so you don't just keep throwing money at the pile.

 

You dont state what kind of truck you drive, but i had the same problem with my Pete and 6nz, What happened was my fuel lines were collapsing under load. Once i replaced them problem was solved