silverbur

Hi, I would like to see if someone here can help me. I'm having a weird problem with my del sol and I believe is the ECU. When i use my ecu the car starts and then after a few seconds the check engine light comes on and then immediately the car goes off. We tried to get the codes but there're no codes, we scanned the car a couple of times and no codes so we checked the main relay and all the signals are working so we check the ECU we opened and it seems to be fine, all the lines and everything looks fine, so we tried another ECU P30 too and is not giving the problem at the moment, so what could be wrong with my ECU?? any ideas?? what can you suggest? Thanx!.