I have done some work on the renix jeep ECU for the 4.0. i liked it because of the fact that its a true speed density ECU. my goal was to see if it was possible for it to be used in a turbo 4.0 application with larger MAP sensor and scale in larger injectors for more fuel. finding the basic timing and fueling tables was fairly easy using winOLS. i have since made basic timing and fueling adjustments to the ECU and it made a world of a difference in how it ran. in a non turbo application all you really need to work with is timing and fueling mapping to have a basic tune that will work. well just giving some info even though you was working with the later ECU thats not the bastard like the one i have as everyone calls it.