I have the 5.3 mp112 and still running the magnacharger tune. Have a volant air box and ngktr6 plugs. Could the volant or plugs be making this lean condition.

 

Get a fuel pressure gauge on that thing ASAP.

 

checked fuel pressure and its around 62-63 psi

 

What is the pressure while you are driving, and hard into the throttle at higher rpm?

 

I had my wife rev the engine and at higher rpms it stays the same. As for driving I don't have a gauge in cab yet.

 

Tape your gauge to the windshield and go drive it. Revving it in P or N won't replicate real-world.

 

Ok I will have to lengthen my gauge hose a bit and drive it, will get back to you. Also I talked to mechanic yesterday and he told me to check for vacuum leaks and check my MAF. Found and fixed one vacuum leak and replaced my maf. But still pulling codes

 

Ok took a drive with fuel pressure gauge on. Mostly stay at 60 psi and at the highest rpm did'nt get but slightly past 60psi. So i'm saying 58 psi at the lowest. Not hearing any pinging or feeling signs of detonation

 

Seems like my fuel pressure is ok. If not what shoud it be?

 

When you go into boost, the pressure should be increasing. The normal rate that I see is 1 psi increase in fuel pressure per 1 psi increase in boost. I usually see around 68 psi (or so) fuel pressure when in 8-9 psi boost. So, your fuel pressure may be a little low when in boost. How is your fuel system set up? How much boost are you pushing with the MP112? Do you have a wideband, or at least a way to read the O2 sensors while driving? Don't give up yet.