Part 2 of "boost problems" understanding the turbo

Ok this should of been the first post but better late then never lol

the problem with my truck losing boost or not always making full boost I come to figure it's possibly a bad turbo or a actuator. First I need to understand how it works better and please correct me when I am wrong.

at idle the actuator shaft should be short as possible (gate is closed so it sends exhaust to the turbo) as I accelerate the gate stays closed as boost rises until it gets to a set psi... Then the shaft on the actuator pushes down opening the flap in the turbo VIA the braded tube going into the top of the actuator. Since I believe the actuator arm should extend I assume it is air pressure pushing on the top of it that opens the flap and "blows" off boost? Now when I go to shift or lift off the throttle the arm is quickly pushed open to evacuate boost pressure since I don't see a conventional BOV? So if my problem is a bad actuator it would be getting air pressure pushed on the actuator too soon ?? If that's the case were is the supply coming from that is cutting my boost short

makes for a long day trying to pull hills... Funny as I said in the earlier post if I shut the truck off even for a few minutes it will regain full boost for a short period of time

 

Ok I watched a few videos and I will check it out . I misunderstood the VNT opens to raise boost pressure then relieve it so with the truck off the lever should be short or long as possible. (Not sure what way on the cummins) and as rpm raises it should do one or the other opening the veins to raise turbo pressure . From other things I read the arm itself on the turbo could be rusted or the veins themselves could have carbon build up. Either way now I have a better idea of what to look for. Thank for the help