Mazda B-Series Pickup Forum : “Where is located the EGR valve ,Thanks”
The EGR valve recirculates some exhaust gases back to the engine intake to reduce oxidized nitrogen emissions. I found a whole thread on EGR valves in the MazdaWorld forums, which includes photos that will show you exactly where the EGR valve is (scroll down): http://forums.mazdaworld.org/index.php?showtopic=13174
Typically, the EGR valve is located on the valve cover gasket... be it a 4 or a 6 OR an 8 cylinder. There will be a smallish rubber hose coming out of it, approximately 1/2" to 3/4" in outside diameter. Most will just pop out of the valve cover gasket with a bit of force. So, pop it out, remove it from the hose, and reverse the process for the new one. When you put in the new one, if it's a bit tough to get back in the hole, take a bit of oil from around the rubber part of the old one and lube the rubber part of the new one that is going in.