C15 Acert rebuild

I would start with checking the charge air cooler, Do you have a turbo gauge and how high does it go? If your only getting about 30lbs of boost you might have an Actuator valve that's bad. Thy can suck up to 1mpg if one of them is out.

 

It would throw a cel if there are actuator issues this is a bridge motor so unfortunately it never had a great track record

 

It is not a bridge motor. The bridge motor was a single turbo that was only manufactured for a year and only found in 2003 or 2004 year model trucks. And there's nothing wrong with any bridge motor that can't be easily fixed by a simple ECM re-flash.

 

I thought the bxs designation made was for the bridge and the sdp was for the full accert lol still the code for actuator issue holds true I think

 

MBN is the only bridge motor serial # prefix. BXS is an ACERT prefix, one of many.

 

If it's electrical fault yes, if its mechanical not necessarily. It could be as simple as a leaking o-ring causing problems and you won't get a code.
To the O/P don't forget to factor the winter fuel penalty. The acert engines are hit with a bigger winter fuel penalty by design.
I have a RE - educated C-13 acert, winter fuel will cost me about 1mpg (I don't idle my truck). Before re-education winter fuel cost me about 2 mpg and my fuel was wildly variable the rest of the year with no rhyme or reason to weight, speed or terrain .

 

What are the rpm at your cruise speed? Sounds like your truck bas short legs. Acerts like to be run between 1200 and 1300 rpm. Anything over it kills the fuel.