Before I went to Florida this spring [20 hours each way] I was getting 19.5 mpg, no smoke ever, and good power, got 19.5 if I kept below 75 and 16.5 when running 85+. About a month after I got back truck started missing and fuel economy dropped to 10mpg. Checked with heat probe and found #5cyl dead so pulled Injectors and had tested and all but 2 were junk so I replaced all fuel and air filters. Now truck runs smother than ever but only got 15 with new injectors and after 4 tanks of fuel is up to 16.5 but not even close to the power it used to have.
On another note, the overhead console ran 1 mpg off before and now it is dead on.
I am trying to figure where my 3mpg and power went. I have 19psi boost at 60 and 35psi max. Fuel pressure is within 2% of demand.
Is there a sensor that could be reading wrong that effects econom. I am thinking fuel pressure or timing

 

You're running 19 psi at steady cruise at 60 mph???

 

Thats what my Snap On scanner says

 

That seems really high. I'll have to take my truck out and run it up to 60 and see where it is. I want to say my 08 was under 10psi at steady cruise unless there was a strong head wind.

 

snap on scanner will read barometric pressure (14.7 psi) + boost pressure, if its reading 19 you are at 4.3 psi (actuall) pressure, witch is normal,

have you oned the truck since new? it could have had aftermarket injectors installed, witch is where the power and fuel milage could have went

 

Hows fuel filter? I run 5-6psi at 60mph or so.

 

Yeah, ok that makes sense. I run 4-6 psi at 60, 6-8 psi at 70-75ish.