Isx oil pressure drops when let off throttle

[Waterloo]

You need someone to look at that, I wonder if he used the correct program/file. The proper file code that he should have used is on the side of the motor on the engine plate. It will read av100***. That would be the first place I check, you will need an Inline 5 or 6 reader to see that in your ECM. You may just have a Volvo or Peterbilt file in there. Ask your buddy if he is using truck specific av files or is he just using the same file for all of the trucks he has done. Until then, I would not drive it. Oil pressure dropping, you need to find out why. May be the programing, may be something else. Programing is where I would start.