I have read on this page that the 2006 5.4 does not have a regular plastic PCV valve in the valve cover. There is a 1/2 inch plastic hose that runs from the valve cover to the "PCV" on the intake manifold. This is a plastic tube about 6 inches long with a heating element on one end and bolts in with a two bolt flange............... Sons truck started burning oil so I assume it might be the "PCV" valve stuck. Pulled the valve ( plastic tube with heating element) and blew thru it. It has nothing inside. Straight open 1/2 inch tube....... Did something fall out ? I assumed there was an orifice inside the tube to restrict the oil vapor flow (PCV) ? Anyone ever looked up close ?

 

@steve(ill)


I just completed a full blown phaser / chains / lifters / followers job on my '04 5.4 and looked at all that stuff while valve covers were off. There is NO PCV "VALVE".


The crankcase is (supposed to be) completely sealed. "Filtered" air is constantly drawn from the passenger side of the Air filter box into the top of the Bank1 valve cover - then through the crank case / timing cover - and out the "PCV" line on the Bank2 valve cover into the intake manifold via that little heater tube you describe. The PCM activates that electrical heater somewhere below about 40º (not sure why). But, that small amount of air is constantly drawn through that path ALL the time. There is never any "positive" crankcase pressure.


As a direct consequence of this design - a significant air leak (un-metered air) entering around valve covers gaskets, pan gasket, front timing cover gasket - OR even the oil filler tube cap would be POST MAF and would result in elevated fuel trims and/or lean codes.

 

that just seems odd that there is no "control orifice" or someway to regulate the air flow thru the PCV line... If you take an older truck and take the PCV out of the system you will suck air so fast that you will pull oil out of the motor and have excessive usage. Just seems like a 1/2 inch ID tube is excessive without a restriction plate somewhere........ Maybe the port on the intake manifold is not in a "high vacuum" area so it don't suck as hard... I don't know.

 

I agree. I was surprised when I figured it out. But it really kinda' makes sense. The air source consisting only about a 1/4" tube (on Bank1) allows only "METERED" and "FILTERED" air to enter the crankcase. A slightly larger suction line (On bank2) - about 1/2 inch like you say - delivers crankcase air to the belly of the intake manifold - where it can be consumed by all 8 cylinders. Being slightly larger, that would basically place a slight vacuum in the crankcase, totally preventing oil vapors from reaching the atmosphere. With the crankcase / front cover / valve covers and everything sealed, it does not change the metered air to fuel ratio at all.

In days gone by - the PCV valve basically had a ball bearing in them allowing "positive pressure" in the crankcase to escape into the air intake - usually outside the air filter. ??? I guess almost the same thing - except the oil vapors collected on the air filter instead of getting burned in the combustion process.