What are the two tubes of the old Corolla throttle?

One is connected with the air intake branch pipe, and the other is used for air intake. The first one of the old Corolla throttle is connected to the intake branch pipe, and the PVC valve (also called the crankcase forced ventilation valve) is a one-way valve. The exhaust gas generated by the crankcase is pumped into the intake branch pipe, and the other end of the exhaust gas is connected with the intake branch pipe to generate vacuum negative pressure combustion. The second pipe is used for air intake, and the other end is connected with bellows connected with air grille and throttle valve, which is directly connected with the atmosphere to balance the pressure of these two pipes.