Rb25det random shut off

[Adrianrb]

So I’ve had my 25det swapped laurel going sweet for ablut a year ago recently ran into an issue where she would just shut off on me.

gradually gotten worse I believe it’s electrical but I can’t put my finger on what it could be.

car will start and run for 2-3minutes no issues-backfires or missing, can rev freely like no tomorrow, then suddenly will just shut off, dash lights disappear and so does the power to the ecu. If you try and turn off and on again the dash lights come on for a split second and shut off again as if a fuse was blowing but all fuses remain fine.

the only way return power to ecu and dash lights to return is to remove the battery for 30 seconds. I have pulled all relays and tested they seem to be fine.

i ran fault codes and sometimes reads engine coolant temp but I don’t understand how that would prevent ecu repower after switching off ignition.

Any help appreciated 

[GTSBoy]

ECCS relay would be my number 1 suspicion. Either it's faulty, or the wiring for it is not right courtesy of the transplant.