I cannot figure this out for the life of me. I thought I would try posting here before I gave up and brought it to the mechanic.
I have an 2006 6.0 diesel. I'm having a weird issue where when I accelerate, it builds up boost to anywhere from 7-10 psi then dumps it to like 3-4 psi and stays there until I let off the gas. It almost sounds like there is a whistle coming from somewhere when it happens. I also cannot build more than about 10 psi of boost in general. When pulling up a hill I have to drop to about 50 mph to keep my EGTs around 1100. If I try to go the speed limit I'll easily go above 1200.
- I've pressure tested at the intake of the turbo and it holds 30 psi with no leaks.
- I've looked at my MAP tube and it's intact. The MAP sensor seems to be working properly
- I've taken the turbo apart and cleaned and lubed it up
- Verified my VGTs don't ever hit 15% or 85%
- I've tried driving with my exhaust loose to rule out a clogged cat
- I tried to do a exhaust leak check by pressurizing the exhaust pipe. I got rid of most of the leaks. there was still a minor leak between exhaust manifold and turbo y-pipe but it didn't seem that bad.
Here are some reference videos of some of the readings
https://youtube.com/shorts/eE9wIWGJeW0
https://youtube.com/shorts/RkQRQCybR18
https://youtube.com/shorts/6jaAVblMaQI
Does anyone have any thoughts? Any help would be much appreciated. Thanks!