7AFE Catch Can setup - confused by oem breathers Options

[atlex]

This isn't a celica I've got, it's a Toyota Sprinter Carib - a 4WD estate based on the corolla chassis, but with either a 4AFE, 7AFE or 4AGE (20V Black Top) engine.

Mine's the 7AFE .. Z Touring, 4WD, AE115 model.

I'm asking here because this is one of the better forums for 7AFE engine knowledge

Photo here: https://trull.org/alex/media/pics/car/carib...ue/on_farts.jpg (sprint (f)hart wheels)

Anyway, I see two breather hoses, and this has confused me a bit. One hose, the left-hand one, has the pcv valve, the other hose, which just goes to another hole in the intake plenum, has no pcv valve. I'm trying to understand why they've got two hoses to from the cam cover to the intake plenum, one of which has a check valve, as this doesn't make sense to me.

Typically if you have two paths between two chambers, and one has a check valve in it, and there is some pressure difference causing flow, the flow will favour the path with least resistance - it looks to me like the pcv valve shouldn't see flow ?

Normally the second breather hose would be run pre throttle body to provide some through-flow under vacuum... and the pcv valve would be in constant use as it would be the only path between the source of vacuum, the intake plenum, and the cam cover..



not my engine but very similar.

I'm thinking to block off the right hand hose on the plenum side, put a breather filter on the cam cover side and then run the catch can between the left hand ports - pcv valve, catch tank, intake plenum..