its true that the jam ecu's are mapped differently, however they seem to work in closed loop all the time, always searching for the best af target.. weve had them on crazy setups in the past.. including me running a td04L at 1.7bar with 330cc inectors a supra pump & a sard regulator..
it seems that anything u throw at them, they try to keep up lol.. this said however, i do strongly reccomend that you get it checked out propperly on a dyno, or buy a wideband & monitor your af (if u can work you way around tuning the car urself, if in doubt though.. leave it alone and take it to a reccomended dyno).
just my 2p
kon