Purpose of evap valve under the intake manifold.
 

I'm trying to chase down a vacuum leak in the evap system and I'm having trouble figuring out how the system works.

Near the carbon canister, there is a "tank vent valve" (also called a purge valve) that is controlled by the DME to purge the carbon canister of fuel vapor under certain conditions. The TVV works in conjunction with another valve near it, the "shut off valve" which opens and closes to let fresh air into the system when the TVV is open and purging the carbon canister.

So what is the purpose of another valve (I don't even know its name) under the intake manifold thats in the same circuit as the TVV?

Vent the tank while your putting gas in.. :cheers: It's activated by the pump nozzle going into the tube. Proximity switch.. and.. and.. they sometimes slide down and don't *see* the fuel nozzle/pump nozzle. It has to be clocked on the alum filler tube just right :)

I was way way.. off.. but instead of editing..

The valve under the plenum vents the fuel pump/gas tank.

But from all I've read, the tank vent valve near the canister is what vents/purges the tank.

If you have vacuum im the tank to purge the vapors you must also have fresh air going in. Otherwise you have the potential to collapse the fuel tank.

I was cleaning my throttle body over the weekend and when I pulled this black/white 1 way valve off of the plenum and blew into it, there was quite a bit of oil inside this 1 way valve. I blew some air in there from the compressor and cleaned out all the oil.

1. This one way valve is suppose to flow in the direction into the engine correct?

2. Why was there oil inside here, what's causing it and what should I check? Could this be the cause of my P0455 and the smell of gas I've been having while idling and hard driving?

Anyone? Thanks