X15 Jake brake is weak at times

[tractortaxi]

Hey all,

Got a 2021 Pete 389, 3.42 rears, eaton 18spd, X15 565/1850 w/ 610k miles, demandated @ 330k but still has VGT. Jakes were working great until recently and now sometimes boost up to 25-28psi but other times only up to 10psi.

I do not currently have access to insite or calterm, don’t even have an inline-6 link. But I can if necessary. Just trying to save a trip to the shop if this is something I can solve myself.

For added info, there’s little to no blow-by, only needs about 2 quarts of oil between changes @ 15k intervals, not losing coolant (other than some cold leaks this winter). Oil pressure has been around 30-32 psi @ operating temp since new. Never been over 240* even when pulling hills. Coolant never over 210*. Also had a recent overhead @ 606k (jake issue was happening before this).

Is this just a case of the turbo vanes getting soot packed and not working right? Boost when pulling maxes out at 39 @ 1500rpm (yes, stupid high, I know) but I regularly climb between 1700-1800 where it sits about 32-33psi.