This one has me stumped.

The truck:
'95 6.5TD KD chip, gear drive, KD exhaust, air box opened, clean air/fuel filters, and the required boost/egt gauges. New vacuum pump and belt/tensioner, and newer OPS and lift pump (both seem to be working fine), oem original turbo with approx 200k miles.

It seems that when I'm running under 2,000 rpm I have almost 0 boost. It never had a lot but would easily pull 5-7# or more if I leaned on it at all. Once I get closer to 2200-2400 rpm boost pressure shoots to what I'll call normal, 11-12# with a bit of the skinny pedal applied. Obviously, with the KD chip and no boost it rolls the black smoke like an old Mack dump truck so I would think the fuel is there, just no boost. The actuator rod on the turbo is nice and tight at an idle too as it should be.

I haven't tested the new pump but the old finger on the hose trick says that it's pulling pretty hard and smooth. Testing is in the plan for tonight.

Thoughts?

Thanks in advance
Big Green