The ABV (air bypass valve) is part of the air injection system, not the EGR (exhaust gas recirculation) system. The ABV takes the output of the smog pump and diverts it back to the air cleaner when not injecting it to the air injection rail. When pumping the clean air into the air injection rail, it mixes with the exhaust gas and converts the CO to CO2 before it can come out the tailpipe. The EGR takes spent exhaust, cools it and sends it back to the intake to dilute the fuel/air mixture to reduce combustion temperatures.