Hello,
Recently swapped in an RB25DET into my 95 240sx and now I'm having issues with the first startup.
I have a new wiring specialties harness, I am getting fuel and spark, and the engine does have decent compression numbers across the board. I have been trying to start with the MAF unplugged. Engine does not make any crazy noises when cranking and was allegedly a well running engine.

Things I've tried:
Stock ECU and Stock injectors (engine originally had Nistune and 550s)
Hand spun CAS and checked for spark. Ensured Injectors are fueling properly.
Fresh spark plugs
CAS appears to be aligned.
Checked fuel pressure. Checked for proper grounds.

At the moment I have the 550s and Nistune back in with a base map tuned for such. It sounds like the engine is igniting fuel when I crank and apply throttle. But it does not sound like the motor wants to start at all. Eventually if I mess with the car enough the plugs will show some soot as well.

Any help on what to possibly look into would be much appreciated.

Engine is an S1 RB25DET
STOCK internals
Q45 TB
Freddy Intake
HX35 turbo
Z32 MAF