UD uses the same programming as Hino. I use my UD software on the Hino trucks as well. The log I attached earlier shows that I'm getting target to actual is pretty close for the VNT and EGR. I've already checked the VNT linkage visually, that it movies when the truck is turned on. I'll check it again to see if I can move it by hand with the truck off. And check for shaft play and stickyness on the turbo.
I'm starting to suspect the turbo after looking at the logs a bit more. At wot when the engine is cold VNT is around 40% after its warmed up at wot VNT is +60%. Cant hear the turbo at all till after the truck is warmed up. My guess is they limit boost to lower when the engine is cold and the effect is more pronounced with a bad turbo.
Thanks for all your help so far.
Interesting, thank you for the feedback. These turbos aren't all that great.
Is scv current target/actual scv current matching? This can also cause periodic low power, but not quite as bad as you're describing.
Interesting factoid: Hino made a great deal of effort to improve the injectors in their engines, putting diamond-like carbon on many of the wear surfaces. They extended the injector warranty on many trucks well past what they had advertised, we just had to clear it with the TSM.
UD did not get any of these upgraded injectors. However, they will still work. You may not be able to program them in (the ecu won't recognize codes starting above a certain number), but it'll run well regardless, without a CEL (in my experience, anyway).