hey my car mysfire on the cylinder 3 and 4 and I don't know what else to do I have changed everything the dist,dist cap, dist, rotor, and still I need help thank's

 

Plugs?

 

no I have changed plugs,dist,dist rotor,dist cap and this start happening since I swap the head on my engine I used to have a d16Y5 and now I have the D16Y8 head so any tips thank's!

 

Check compression/ trace all your work back/

 

how can I check my compression?

 

Are you messing with me you just changed a head?

 

well my car runs strong on all gears just misfire on 3and 4 when is at low rpms before the 3500 RPM's and it doesnt do it too often but it does! and I always get my OBD code PO303&304 so I don't know where else to check! do u gusy think I have to change the ECU as well?

 

I have the block with the pistons and everything out of the D16Y8 is sitting on my garage I didn't want to put all the engine tho! should I have?

 

Hold on let me get some stuff.

 

I din't wanted to change the whole engine since I don't have much help but I would if I have to to make it work