I did a search for backfiring and came up with 100 results and didn't feel like sorting through them, but anyway, i've got a 13b fuel injected and it tends to backfire ALOT on deceleration sometimes even shifting or just letting go of the gas, the air pump was removed when i baught it and all of the cats gutted... i assume the air pump was attached the the air control valve? that's still on there, i've got a blocker plate and have no idea where it goes i took off what i think is the acv and blocked it where the blocker plate fits perfectly and the car won't even idle, this thing that i think is the acv has 3 ports that are just open, that might be the cause of this backfiring? and how am i supposed to put this blocker plate on?

 

I am having that problem right now with my 13B-T 2nd Gen.

Check the intake and make sure you sealed the blockoff plate properly (gasket or gasket goo).

The backfiring seems to be caused by air intake leaks.