98.5 24v a/t 3.55 78k bone stock. originally got 18.5+ average.
after recall 8001 for nox emishion, milage instantly droped to 10 empty and easy and 7 pulling hills or towing ( less than 10 k lbs ) with noticeably less power. after several trips to 3 dealers,dodge p.r. manager said 7-10 mpg was low but within average. went to cummins they said they could find nothing wrong, had seen the problem many times, said it was the new flash but could not restore to original and no new flashes were avalible. paid for reflash with no change.

looking for way to restore to original or better

 

Bad sensor of some kind? I don't know what kind of sensors that they have...

I would suspect that the problem is in the computer... Wonder what an aftermarket programmer could do.

Let's see if I remember... NOx reduction is achieved by reducing cylinder temperatures. This is often done through retarded timing. Maybe your's is stuck in retarded mode. Notice any power drop at RPM?

Who knows what they did to the program in attempts to decrease NOx. Anybody else have this problem?

 

How in the world does Dodge or Cummins expect a pickup to use just as much fuel as an 18wheeler? (with the 18wheeler having an 80k load, no less). I think 18.5 is marginal, unless you have a heavy foot.

Check your lift pump output. Your only other recourse may be a new pump or ECM. Talk to some aftermarket guys and see what their programers can do for ya. I have a friend with a 00-ish 24v auto that went from 19 to 25mpg with "some chip". Even if it cost $5-750, it can pay for itself in no time at $4.80 a gallon.

Daniel