zj 4.0 getting it from running lean to rich

[98zjstroker]

Ok so I have been doing a lot of searching when it comes to putting a 4.6 or 4.7 stroker to replace my 4.0 motor. One of the problems that I found from some was that the 4.0 is built to run lean which kills the power and makes it even worse on the 4.6/7. One person (via youtube video) even took it to a dyno place to have them adjust the ECU after he put in the stocker but they were unable to. I have read that the mopar ECU cannot be re-programed. So is there a way to make it run richer then stock?

 

[a_kelley]

All jtecs can be flashed. Look into sct and I forget the other one.. But it can be done.

 

[Jeff B]

I am building a 4.7 stroker now. When finished, Ill contact these folks for tuning. High Performance Auto Engine Service | Hesco

@Jody Treadway may be able to add some insight also.

 

[Jody Treadway]

One of the problems that I found from some was that the 4.0 is built to run lean which kills the power

This is not true. An engine (gasoline) makes the most power just at the point of running too lean and causing detonation.
A lean mixture will burn longer which in turn creates more energy.
I will add to this in a little bit when I don't have my hands inside of a broken Dana 35