It is my understanding that there is a difference in the 5.9L engine after 2004.5. If I am correct, what is the difference? Is the 2004.5-2007 better then the prior version? If so, why? Actually, a friend tells me the 2004 version is better on fuel economy but I can't find that written anywhere...

thanks in advance...

turbo, injectors, pistons, ecm/pcm, cat are all different.
turbo is bigger on the compressor side allowing slightly more boost.
the injectors have a different hole count/spray angle for emissions purposes.
the pistons to work with the injectors.
the ECM is stronger/faster.
the 04.5 has a CAT the 03-04 do not.

 

thanks Scrappy, it must be the lack of the cat cvtr in the early model that he is talking about...he seems to think the earlier version is a better motor, better fuel economy...

 

The 04.5, which were built after Jan 1, 2004 have a third injection event which can hurt fuel economy slightly. The early 04's have only two injection events. The early ones have a reputation as having better fuel mileage, but if I were looking, I wouldn't worry about one over the other.

 

very helpful, thank you...