rb25 injector cut out while running !!!HELP!!!

[motoman399]

well my buddy has an rb25 in his s14 and we just put his sweet setup on it and we got it running today. while we had it idling it all of the sudden dropped a cylinder. we traced it down to the no.1 injector not firing. he said that it has happened to him before with the stock injectors. so that leads me to believe that its not the injectors (pretty new 740cc nismo's). i have seen that in parts of the car someone has done not the best job at wiring some stuff (lots of butt connectors and scotch locks) but that was mostly in the alarm i did see some butt connectors for parts of the ecu wiring. so can anybody direct me on how to figure out why it dropped the injector signal. oh and he also has an apexi power fc. thanks and here is a couple pics of his setup