Duramax Diesel boost Problem

Dale , im having an issue with a stock tune i was playing with. It's for a Lml 2016, tune works but it throws a code P0299 code and derates the engine. I've noticed it really consistent when I'm doing about 70mph and I hit a little incline and I'm trying to keep that speed, Boost doesn't want to move much unless I put the pedal to almost the floor. If you drive it like I didn't car about the fuel mileage it doesn't seem to ever have the code come up. Just curious where I should start looking for this problem. I thought possible a turbo issue like the vanes were sticking but I had another truck i tried it on and it did the same thing.

I would start by logging desired boost vs. actual to see what the story is in the data. I suspect the truck is unable to achieve the desired boost target for some length of time and then set's a P0299.

Are you commanding more boost than the truck is able to make? Is your desired boost set higher than stock?

-Nick

I did log it and its struggling underload at lower rpms below 2300rpm by 10 psi sometimes below desire and defaults the vgt to full open and stills struggles a lot . I also logged fuel pressure desire to actual and its right on. Also I logged the fuel command mm3 and its right on what the file is . It does seem like I'm choking it out because it has the bost fine at full throttle lower speed.

Is your desired boost set higher than stock calibration values?

No. The mack desire is 35 psi barometric pressure. And these tables haven't been edited.

We're at the point where I don't think I can offer much more help without a datalog and tune file.

It may be that you've loaded a lot of torque early in the pedal and are lugging the engine in a load/RPM area it never would have seen in factory conditions. Just throwing darts at the wall now.

Nick