I have a 2001 Honda prelude type sh, I just finished an engine swap both engines were h22a heads and h23a blocks, every single sensor is brand new, every gasket is brand new, every single belt is brand new. distributor cap, rotor, and icm is new along with plug wires and ignition coil. I can’t seem to get this car to start, it cranks and tries to turn over but then quickly goes back down to 0 rpms and does this over and over again, there are no codes, I can hear the fuel prim when I turn the key and it’s got spark. Does anyone have any ideas?

 

which ecu youre using?

 

I am running my stock ecu for the type sh, it is what I was using before

 

So it cranks over fine and fires? Like it runs but won't idle? Or does it crank but not fire?

If it does fire:
Check for vacuum leaks, check the fuel pressure regulator & its vacuum line.

If it doesn't:
Check for spark @ the coil or @ a spark plug, check main relay (sometimes they can stick or work intermittently)