Engine/Transmission (1998.5 - 2002) "Boost 32lbs usuall @ WOT; today 15lb? What's up?

[RobbyRam]

"Boost 32lbs normally @ WOT; but today 15lb? What's up?

OK, all you 'Gearheads'! Please help with your knowledge if you can!

(Please read my signature first for added info. )

Yes, the truck still runs great!!! Pleanty of get up and go! However, I just noticed today that my maximum boost, which used to easily top out at 32lbs on my Westtach gauge, now reads only a max; 15lbs.



Power 'seems' the same, S. O. P. , when at "Edge comp" setting 3x3, and even at 5x5. My "Cummins 'Quick Check II'" scanner confirms the same low boost numbers,(15. 35lbs), and my 'RD Harrison' scanner shows no 'codes set either.



I have my gauge tapped at the 3/4" manifold outlet behind the fuel filter and it has worked perfectly for over 2 years.



I have checked for boost leaks; at the wastegate=none

;at connections and clamps=none



My fuel milage is an unreal 20. 2 mpg's, (confimed this Saturday

with a heavy freeway traffic trip to the "A's / Giants" baseball

game from Sacto to Oakland Saturday night, 24 of us, divided equally for each team, and with a tailgate party. )



Sorry if this is T. M. I. , but I wanted to add as much information as I could in this post as my wife, as I type, is choking me because I spend too much time on the TDR!



So anybody, PLEASE HELP with your knowledge!!!... and... HVAC! Where are you with your expertise???

Thanks in advance, Bob in Sacramento

 

[A Johnson]

Have you pressure tested the charge air cooler?Intake, or gridheater gaskets?



Also possible the waste gate flapper valve is broken inside the turbo exhaust housing, dumping all the exhaust before the turbine wheel.



When you checked connections and clamps did you use air pressure or just check with a wrench?



A Johnson

 

[RobbyRam]

How do I 'pressure test' the turbo system?