i have a 91 240sx with a vq35de swap, it had an 05 vq35de rev up but it threw a rod, i got an 03 engine to replace it due to the 05 motor being too expensive, the engine is installed the car will crank over but wont fire up, (05 vq35de rev up)the old motor had 6 cam position sensors, where as the 03 motor i bought has 2, what can i do to make the car fire up all the way? I kept the same wiring harness because it was all wired up for the 240sx to run with the vq35de. The car drove fine untill a rod went threw the block.

They have different ECM's I believe. Does your car have the BCM, IPDM, and all that Jazz or a is it a modified system.

I'm not sure, it has the regular ecu though, have an 03 ecu and and 06

That is important to know because if the cars has the Nissan Anti-theft still then the ECM might be locked out. Find out what all for engine control you and let us know.

The '03 motor will not run on the Rev-Up ECU. They are completely different. The ECU must match the year/model of the engine.