[olddog]

If the information I have found is correct, the factory (Ford) tune on an EEC4 for the 5.0 mustangs (which is what Chris uses) purposely runs the engine very lean at light load conditions, especially at low rpm. Perhaps to get the cats hot. The maps I have seen go as lean as 16:1. In my conversation with Chris, I got the impression that he feels the factory engineers know best and all engines are close to having the same needs.

With that said, the closed loop lean condition may well be that the maps are telling it to run that lean. That might have woked ok for a 5.0 with cast iron heads, egr, closed chamber with some squish in it, and mild cam. An FE most likely has very different needs.