ok so i have a a 93 dx civic coupe
block is a d15b1 and head is from a93 ex unsure
maybe a z6 running a p28 computer everythings
ran right hoses vacuums etc the only thing i can think of is timing may be off
does any one know of anything else that could be the reason of back firing
as of right now im only throwing vtec syl. and pressure codes
helpp me please lol any suggestions

 

So your running a d15 block with a d16y8 head right? Double check your spark plug wires. Also double check the timing making sure they lines line up correctly.

When I first did mine in my crx my didnt even start because spark plug wires 1 and 3 were mismatched.