Hi All,
I cant figure this out and need your help. On the side of the throttle body on TPI cars there are two hose fittings. According to my emmisions sticker on the hood. The top (1/2" nipple) goes to the crankcase ventilation (3/8 fitting) on pass. side valve cover. The bottom (3/8" nipple) goes to the charcoal canister purge. Well if you look at the design of the throttle bodies and see how they route the vacuum threw them it doesnt make sense to me.
The top 1/2" goes over top the throttle body to a small port that only will pull vacuum when the throttle body opens. Wouldnt this stop or restrict the constant flow of vaccuum to circulate the PCV sytem? The bottom 3/8" pulls vaccuum constanly. It doesnt seem proper. Should it not be the other way around? Is my sticker messed up on my hood?

Please help me out! Confused in KY
kyrenegade

 

The hose that goes from the TB to the valve cover is the FEED side of the PCV system. Fresh air is drawn from the TB INTO the pass. side valve cover through that hose, circulates through the motor picking up blow-by gasses and is then drawn OUT the other valve cover, through the PCV valve and into the intake manifold to be burned with the rest of the air/fuel mix. So that TB hose doesn't get vacuum- it's a fresh air feed that picks up air IN FRONT OF the throttle plates, where little or no vacuum exists under any amount of throttle opening.

 

Thanks for the reply! I guess what has thrown me was the size of the nipple coming out of the side of the throttle body on the top. Its a 1/2 inch compared to where it feeds into the valve cover 3/8". Wonder why they made these two different sizes?

Thanks Again,
kyrenegade

 

Interesting, so does the ball check valve work in the reverse direction on the right side of the engine?