No Boost

[lggraver]

2004 f350 doesn't build boost. At wide open throttle I only can get 13 psi out of it. I have checked every where for exhaust leaks and boost leaks and it has none. there are no codes that come up. I am at a lost. I have cleaned the ebp tube and sensor. I had the turbo off to do a egr ****** and now that I put everything back together I am not building boost. It used to build 29 to 30 psi. Now it barely does half that. it isn't smoking at wot or anything. turbo still makes it whistling sound at idle. it is straight piped so there is no cat. I am at a lost on what to do next.

any help will be greatly appreciated

Thanks,

Levi

 

[DEEZUZ]

Make sure map boost line is on. Right side of intake up to map sensor

 

[Wildman]

Could be turbo vanes are stuck open. That will cause low boost unless you have a very heavy load on the engine to allow it to spool the turbo with the vanes in the open position. It's a common problem on 6.0 engines, typically caused by carbon buildup, but can also be caused by a failed VGT actuator or circuit issue.