losing boost

[TylerP92]

ive had this 2000 F250 for bout a month now. i live in alabama and it doesnt get tht cold but if its aorund 45 degrees or lower and the truck is cold it makes a loud hissing sound when i give it a constant throttle and i lose all my boost. it stops hissin when u give it more throttle and when it warms up or if the temp outside warms up it usually stops.now it does it some even under full throttle. any ideas?

[jesilvas]

First:
Second: Search man.
It's normal.
Here - http://www.powerstroke.org/forum/
Then here - 99-03 7.3L General Discussion - Ford Powerstroke Diesel Forum
Then - Winter Operation, Hard Starting, Hissing Sound Etc...
And - Troubleshooting GPR & GP's

[machinestheman]

sounds like possibly your egbpv and the hissing is the engine fighting essentially a jake brake i am in ga and just disconnected the thing do a search theirs tons of good material in here to give you more info good luck