just to clarify this thread a little
the 3.stage d15b was made in 95-00 in japan which corresponds to usa 96-00
it is NOT the jdm equivalent of the d15z1
which was 91-94 in japan...92-95 usa
for anyone buying a jdm d15b there are probably 5-7 variants of this motor.
japan simplifies the stamping.
88-91 jdm d15b uses the d15b7/d16a6 style head
92-95 jdm d15b vtec (unique crank & rods)
92-95 jdm d15b non-vtec
92-95 jdm d15b vtec-e
96-00 jdm d15b
96-00 jdm d15b vtec (3.stage)

and i think there are a few more

its also funny to watch people complain about not having a wiring harness
you all dont realize all the jdm cars are rhd and the wiring harness is 180? off from usa...making the wiring harness useless except for the plugs i guess.
but all the plugs are available off usa cars from different sensors.
you just need to learn how to depin the connectors...
its fairly simple if you take a minute with a care, some needlenose pliers, and half a brain
depinning the ecu connector i use a sewing pin...a bit harder to do.

also worthy of note...japan doesn't have emissions...
so no jdm motors are going to have purge valves if you use an american computer.
you will have to tee off one of the intake manifold ports for purge canister.
and tee off again for the purge valve vacuum source.
fuel pressure regulator would work for the purge valve.
and the canister i guess could tee from either the brake booster (before the one way valve) or the pcv line (before the pcv valve)

also to run a d15z1 or equivalent jdm motor you will need the egr controller
this is the black box on the firewall
few swaps will come with this...and it increases your gas mileage for sure.

That brings up a good question...I've thought about having the VX trans rebuilt (I still have the D15z1 engine/trans)...is that a big deal, who would be reliable/reasonable to do it?

Also, the jdm motors are missing the vtec solenoid oil pressure switch. I was scratching my head for a day or so wondering why I had an extra connector when I wired mine up with a US harness. So, you will need to purchase a oil pressure switch if your motor does not come with one installed.

What is the right ECU for a JDM D15b engine? Im having trouble trying to find out why my friends car failed smog here in Los Angeles, CA. The car passed the emissions portion fine, but failed because of timing. This is his car:

92 Honda Civic CX w/JDM engine swapped in. (car was bought this way)

ECU I think is a P05-A00

What could be causing the timing to make the car fail smog? He's going to the state ref to see what can be done with the car.

Thanks in advance for the help.

again
there are many versions of the jdm d15b
all of which use different computers
you need either the factory computer for the motor.
but if you are switching generation model of car / shell then you need the ecu that closest matches in that generation.
there are usually better options then others.
but first you need to know what motor you have.

its probably a 96+ jdm motor which has the obd2 cam gear and he is using an obd1 computer...
there are options but you must match the cam gear to the computer because 96+ timing in the computer is much much different then the 92-95 motors/computers...
putting a 96+ motor in a 92-95 car requires use of the obd1 cam gear.
the cam gears are offset half a tooth between generations causing over 9 degrees of timing at the crank pulley

He should find a P07 ECU.