Jeremy D.

Good evening,

I have a '93 4Runner with the 3.0L V6 engine. I am currently reworking the air intake to eliminate restrictions and make it look (and sound) cooler. There are three breather hoses running into the 3" intake pipe; they measure 3/8", 1/2", and 5/8" I.D. One of them goes into what I believe is the valve cover. The other two connect to steel tubes that go down under the intake manifold.

My question is this: do these small hoses need to be connected to negative pressure, or can I shorten them and install paper breathers on each hose?

Thank you!

Jeremy

Levinz11

The one that connect to the drivers side VC is for the PCV valve.

Jeremy D.

Am I OK to put a breather on that one then?

TNRabbit

I wouldn't. I'd keep stock. Toyota was pretty smart when they designed these engines; that's why they last forever....

Jeremy D.

Sounds good, I will try to find fittings to make that work. Thanks guys.

RBX

check all of the isr mod threads, youll get plenty of good info about what needs to stay and what can go.

dmwahl

I don't know about the 2 steel ones, but the valve cover needs to breathe to keep volatile gases, water vapor, etc from building up inside. If you remove the ventilation you probably won't see immediate problems, but long term will develop problems like corrosion and sludge buildup.

The other two may be crankcase ventilation?? If so then the same reasons apply.

There are also emissions reasons for all the various breathers and ventilation systems on modern engines.

My advice is to leave all of them as they are.

Jeremy D.

I'm talking about giving each hose a separate breather instead of tying them all in to the main intake hose. do they need to be connected to negative pressure?

dmwahl

If Toyota went to the effort to put them in there then I'd say yes. If you can take some pictures of them and where they go that would help.

Jeremy D.

...easier than taking one the ones circled in red are the two that I can't identify.

TNRabbit

That's part of the PAIR system. If you don't understand it, you shouldn't try to bypass or change it.

dmwahl

The PAIR system injects air into the exhaust to help burn any unburned fuel. Won't affect performance to keep it or remove it. You may run into trouble with emissions tests though if you remove it, so I would leave it in place.

Jeremy D.

that's the info I needed, thanks.

Wrenchinjoe

The larger hose circled in red on the left feeds filtered but un-metered air to the PAIR valve. You can eliminate the resonator (plastic box lower right in the picture) and route a new hose from the PAIR fitting you circled straight to the top of the air cleaner box. That removes some engine bay clutter without risking emissions testing issues.