I have a 92 hatchback CX had a D15B8 in it the head cracked on it I assume (#2 sparkplug hole was filling with coolant) But I had a B7 motor with a good head so I swaped the head took out the P05 ECU for the 8v and hooked up the P06 for the 16v... It was junk had no power backfired and just ran like crap so for the hell of it I put the P05 back in and the car runs great any ideas why this is? The only B7 part is the head absolutly everything else is off the stock B8.

 

Throwing any check engine light codes, like an O2 sensor one? Unless you have a California spec CX, your car comes stock with a 1-wire O2 sensor, where the P06 will be looking for a 4-wire one. Just throwing that out there.