endlesspwr

brought 96 s6 rx7 recently with sum modded parts,down pipe,midpipeand catback,hks pod filters and hks fcon v with gcc ecu. engine blew up afta a mnth of owning it causing full rebuild including new rotor,seals,turbos,rotorhousings etc, mechanic tried 2 turn ova car and it wouldnt start, so he instaled stock ecu ,car started and ran well, but want 2 find reason why hks fcon wouldnt wrk considering it was working prior engine rebuild, please help as im still learning about my car and dont really want 2 keep running car on stock ecu

regards wade