Lost fuel avg

Any visible soot on manifold indicating exhaust may be leaking...?

Do an injector cut out test yet? And reverse- run it on 1 injector at a time (rawze claims to do it this way)

 

Seems to me your truck is acting the same as gasoline engines when the 02-sensor is gone.

Leak in exhaust manifold = less "burnt gasses" in the downstream sensors

less burnt gasses per "volume of exhaust" (as expected by sensor reading) triggers the ECM to command injectors to "push more fuel"

More fuel (as executed by injectors) = bad fuel econ

This is why cars with bad 02-sensors have worsening fuel economy over time.

 

I agree with @nax. The manifold needs resealed. In my experience, sheered exh bolt/studs from manifold creep is caused by either not warming up truck, hot fuel settings, or malfunctioning injector. Pull the manifold and look at head port. Fuel will be black and wet, oil will be ashy around vavle stem. I am betting on fuel. Probably bad nozzle tip or cracked body. I always use new quill tube and line from rail when replacing injector. Newer ISX also have injector cal codes like CAT's and Detroits had so need someone with INSITE to change that for you. Getting broken bolt will be fun. Every broken bolt scenario is different. I prefer the mig weld technique myself. It is a patience game. Good luck!

 

Dude, you are cooking your motor. I bet you are well on the way to melting a piston and dropping a liner, if you are not already there. Who did the delete? And do you have a pyrometer on that motor? That would explain the busted manifold bolt. High heat. Explains #6 injector too. Bad delete.

You need to head over to Rawze.com, more knowledge there than you will find here. Sad to hear this has happened.

 

I find that response incomplete...

What EXACTLY was the test?

Injector stuck on "OPEN" or "CLOSED" or NO response i.e does not actuate? ...which one?

 

No, it is not the cold weather. The 2250 is a funny motor, liner issues and if a delete is not done properly all of the symptoms you are describing are the outcome. Which in most cases is an in frame. One question though, before we panic, did they weld up the SCR box? And are you running the factory HP or did you have then bump it up? Find out what they did, what they plated and or removed. You still have the factory turbo?