I was just messing around with the vacuum "rats nest" from an S5 on my S4 short-block. After getting the nest set where it goes, it seems impossible to use the S4's EGR valve, or any valve for that matter!

I just noticed that Mazdatrix does not have an EGR valve even listed for the S5.

If the S5 doesn't have an EGR valve, then what does it do to control EGR?

In the end I'm probably going to put a block off plate on it, but this is something that intrigues me.

 

s5 doesnt have egr at all. the s4 engines really have small egr passages, they didnt need that much egr. the s5's prolly got by with the better/faster ecu