Im having the same problem. Just put a rb20 in 32 rollin shell. It cranks over and sorta backfires alot but no start. i checked fuel to the rail and thats good. spark is good. First cas i had in it was oviiously f#@ked cause wen i put a spare one in it sounded more like it was gonna fire.first one was makin it sorta die. Ecu code 55 so thats all sweet. All earths seem sweet. Would a few blocked injectors cause wat ive explained or anything else i should check