7.3 SD with Low power low boost

[Grady J]

I have a new to me 7.3 powerstroke and i'm hoping someone can point me in the right direction. This truck came with a superchips tuner and was in performance mode when I bought it. The EGT's were high and I noticed a lot of black smoke, and only about 5psi of boost. The first thing i did was return the the superchips to the stock setting, and boy oh boy the thing was gutless, were talking a N/A IDI could blow the doors off this thing. No boost whatsoever, but also no smoke which i thought was interesting. From there I assumed boost leak so i made a boost leak tester and found a massive boost leak at the passenger intake plenum, the leak was so bad i couldn't pressurize the system at all. Interesting note, the plenums were not stock they are aftermarket aluminum. I figured if one side was leaking the other side couldn't be too far behind so I re-sealed both plenums with motorcraft RTV. I also noticed when i took the turbo off that the up pipe collector was loose and covered in soot, so i replaced the up pipes with bellowed up pipes. I put everything back together, performed another boost leak test, which there was a few small leaks at the IC boot connections, so i fixed those, and although it is slightly better the truck is still a dog that can't get out of it's own way. At WOT I get zero boost until i hit about 2500 rpm in 3rd gear at which point I hear the turbo spooling and my gauge jumps up to about 5psi. I've driven many 7.3's in the past so I know this is not normal. With those exhaust and boost leaks fixed my next thought was directed to the MAP sensor. The torque Pro app it shows 12.2 psi with KOEO, I live in Northern Utah which is around 4500 above sea level. I thought that number should be closer to 14 psi so I unplugged it and took it for a drive. The truck runs so much better with the MAP sensor unplugged, throttle is way more responsive, At WOT i can get up to 10 psi boost with hardly black any smoke. So i figured the sensor was bad so I purchased a new motorcraft MAP sensor, but this made no difference. Anyone have an idea of where i can go from here? One thing i noticed yesterday while swapping map sensors is with KOEO and the MAP sensor plugged in the wastegate solenoid clicks non-stop, but with the map sensor unplugged the solenoid stops clicking, Is this normal? I should also mention that the turbo is not stock, it looks to be a fairly new Spoologic turbo, not sure which model, the wheel looks really good with no in and out or side to side play. Also I should mention the truck has 239k miles on her. I'm at a loss here guys. Thanks in advance.

 

[Black dawg]

never have driven one with the map sensor unplugged, must be following a default fuel map based on rpm/tps?
Is the hose from the intake to the map sensor restricted in any way? They will make no power if the map never gets boost.
Might want to make sure that turbo is properly sized for a driver, and not some big fuel/big hp turbo.

Also, not all programmers return to an actual stock tune, usually their version of a stock tune. Have seen many weird issues from that.

 

[Grady J]

never have driven one with the map sensor unplugged, must be following a default fuel map based on rpm/tps?
Is the hose from the intake to the map sensor restricted in any way? They will make no power if the map never gets boost.
Might want to make sure that turbo is properly sized for a driver, and not some big fuel/big hp turbo.

Also, not all programmers return to an actual stock tune, usually their version of a stock tune. Have seen many weird issues from that.

It's my understanding that unplugging the the map sensors returns it to a default setting, which is assuming sea level. The hose is not restricted, I pulled it off and blew compressed air through it to verify.

That's the thing about this turbo, I can't find any part #'s on it, judging by the images on Prosource diesel, this could either by a stock drop in, a stage 1 or a stage 1.5, i just have no idea which one.

I did not know that about programmers, it's a cortex superchips tuner.

 

[Grady J]

Also, not all programmers return to an actual stock tune, usually their version of a stock tune. Have seen many weird issues from that.

You nailed it here. i put the tuner back on in the economy/mpg mode and problem solved, 20 psi at WOT and plenty of power for what I need. For whatever reason the stock tune on this superchips tuner turns the truck into a slug. Thank You!

 

[Black dawg]

Nice.
Have seen so many problems with programmers and chips in the 7.3 trucks, that I always tell people to leave them alone if they run good.