grachman

re1991-1993 240sx

Figured this out. You definitely need the AIV to pass aircare in British Columbia. You dont need it in California(you only need it for visual inspection) because California ECU's are different. YOu stay in closed loop during idle. ie the O2 sensor controls mixture at idle. British Columbia may be the only place in the world that needs the AIV to pass emissions. If you have an idle test and you live outside California, it is likely that you do need the AIV to pass, however.
non-california 240sx's will be rich at idle. the aiv supplies air to cat so it can burn off the extra fuel. if you measure richness at the o2 sensor you will be rich with or without the aiv.

rainyD

on the other hand, with a standalone system ie: microtech, shaved AIV.. can fine tune the idle, and with a good cat passes aircare np. show up sitting hella low, and you don't get a driving test.