2005 GMC Other

Engine Performance problem
2005 Other GMC Models 4 cyl Two Wheel Drive Automatic 206, 00 miles

I own a GMC W5500 Truck, same as an NPR, no codes are present, the problem is when I decelerate from road speeds or Hwy speeds it screams. It has a turbo and an engine brake.

I checked the hose to the waste gate and there is no air pressure present to activate it when I decelerate.

If I wire it open, no noise, but no power either. Any ideas? Is my turbo weak?
Peter K
May 23, 2010.

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