Well i've got all the necessary parts (and then some) but the y5 from the HX uses a 5 wire primary o2 sensor and the y8 uses a 4 wire. what the heck am i supposed to do with this 5th wire?? the ecu will be a p2p-a12 so i would imagine it would throw a cel if that wire is just left open

 

Bump

 

you don't do anything with the "5th wire". match the wires for the 4 wire and go.

 

So you're using the wiring harness from the HX and are concerned about the 5-wire o2 plug?

 

yeah i'm just wondering if the p2p (EX) ecu would even realize that the primary o2 is a 5 wire

 

you can't use a 5 wire o2 with it, if that is what you're asking. they are completely different.

 

no i got a 4 wire o2 sensor but i was trying to figure out after i rewire the connector to accept the 4 wire if that 5th wire would for some reason throw a check engine light. but what you said earlier kinda makes sense. like the p2p ecu won't even read the 5 wire o2 so it won't even matter what i do with the 5th wire. it shouldn't throw a cel because it's only reading a 4 wire.

 

Ok simplest way to do this is to run the Ex harness along with the ECU. Converting the Hx harness to a 4 wire is kind of a pain and the Ex ECU will not work with the 5 wire O2 and the 4 wire sensor will not plug into the 5 wire harness end not to mention the 5 wires O2 is tied into other sensors that the 4 wire is not. The Hx harness will also have unneeded wiring that the Ex head will not use so running a Ex harness will clean thing up a bit. I looked into this when I did my B series swap in my Hx and it was much easier to get a $50 harness off Ebay or a junk yard then to mess with all the extra wiring BS. I am not shy about wiring in the least as well.
To get the most out of the Y8 head you will want to run the intake manifold and get a header and Ex cat and even better if you can is to run higher compression pistons since the Y5 is lower than the Y8. You will also need the Y8 injectors since the Y5 injector are much smaller.