New to this site: Where and what is the PCV valve? Where are these hoses supposed to connect?

[JOSHUATREE]

My 1994 explorer (4 door limited) has been having some troubles. My idle is not even, I have had the air tubes pop off the tree with Transmission fluid on them. I have looked around and see that the modulator needs to be replaced. I am changing spark plugs and wires. I am heard that the PCV valve could be causing trouble... What and where is that? Also one of the tubes on the "tree"(is that what it's called?) is capped off and I have an open air port below it. Where is this supposed to connect?
BELOW: capped intake

BELOW: open tube that blows out hot air

Below: Little port next to the one connected in center of pic

I just finished taking the old spark plugs out have most of the new wires and plugs in: before someone says it I didn't mess up firing order. Help me Obi Wan Kenobi ..I mean Explorer forum you're my only hope.

 

[Rick]

In the first picture you can barely see the PCV valve through the sludge. It's attached to the hose that goes into the intake manifold.
It's slightly silver in color and below the vacuum tree.

Sorry I can't identify the open line. Maybe someone else can.

 

[JOSHUATREE]

In the first picture you can barely see the PCV valve through the sludge. It's attached to the hose that goes into the intake manifold.
It's slightly silver in color and below the vacuum tree.

Sorry I can't identify the open line. Maybe someone else can.

Thank you

 

[larrydd999]

That open tube looks like one of the two DPFE supply tubes. The DPFE sensor is the gray box just above it. There should be two rubber tubes (rated for a high temperature - silicon or some such) going into it, one on each side. You probably are getting a fault code as a result of missing the tube.

 

[JOSHUATREE]

That open tube looks like one of the two DPFE supply tubes. The DPFE sensor is the gray box just above it. There should be two rubber tubes (rated for a high temperature - silicon or some such) going into it, one on each side. You probably are getting a fault code as a result of missing the tube.

Brother you just saved the day, In retrospect I should have gone through some trial and error. It seems so simple now.

 

[92exp4x4]

You can get a kit from rockauto to replace those special hoses. They are heat resistant silicon rubber for the EGR system.

PCV, stands for positive crankcase ventilation. It allows unburned vapors that have made thier way past the pitons/rings and into the crankcase, be sucked into the intake and burned. In the early 60s cars had road draft tubes that accomplished the same purpose. Only problem is that these vapors are extremely pollutive and smell bad. A clogged PCV can cause high crankcase pressure to force oil out of the seals and even blow the dipstick out in extreme cases. It also changes the mixture as the engine is pulling less air as its not getting the metered amount through the PCV system. The pressure is generated by compression leaking past the rings while the engine is running. If you have heard of older engines having excessive "blow-by" thats what this means.

 

[Rhett]

In your second pic, it looks like someone has capped off one of the EGR vac ports.

The one that's capped off, is supposed to connect to the open DPFE port...the one that larryddd999 mentions.

 

[shucker1]

In your second pic, it looks like someone has capped off one of the EGR vac ports.

The one that's capped off, is supposed to connect to the open DPFE port...the one that larryddd999 mentions.

Isn't the DPFE sensor only connected to the Upstream \ DownStream side of the EGR flow tube?

I didn't think it connected to a vacuum port.

It's set up like that on my 5.0L 98

May be different on a 94.

 

[92exp4x4]

Isn't the DPFE sensor only connected to the Upstream \ DownStream side of the EGR flow tube?

I didn't think it connected to a vacuum port.

It's set up like that on my 5.0L 98

May be different on a 94.

You're right, this thing has been messed with. It looks like its missing the EGR vacuum control valve and filter too. Its supposed to be mounted to the bracket in the 3rd photo, unless its hidden. The computer controlled valve controls the amount of vacuum to the EGR valve itself. I wouldn't worry about the plugged port on the vacuum tree, as most explorers have 1 plugged port. All of mine do, some 2 if it has a manual trans. I would be worried if you have an open unused port.

If I think of it tomorrow I will post some pics of my truck for comparison.

 

[92exp4x4]

Got some pics, first is the general picture. The PCV is circled in red, the vacuum control solenoid is circled in green and the special EGR hoses are pointed in blue.

Next pic, the computer regulates vacuum to the EGR valve(left arrow, silver pancake thing) from the vacuum tree(right arrow) with the mentioned solenoid (circled). There should be small vacuum lines from tree to solenoid to EGR.

Final pic shows the high temp hoses. Not the rusty pipe or black tube in the foreground. They are the newer ones behind them. They carry exhaust gases from manifold to the DPFE sensor. These hoses are two different diameters and connect as shown. Both from EGR tube branches to DPFE. The stubs should be different sizes on both ends and match hose to hose.

Be careful messing with the metal EGR tube. They like to break off at the manifold. I have had two do it and it led to me doing a lot more work than I planned on. I hope this helps.

 

[Rhett]

Isn't the DPFE sensor only connected to the Upstream \ DownStream side of the EGR flow tube?

I didn't think it connected to a vacuum port.

It's set up like that on my 5.0L 98

May be different on a 94.

I thought his pic WAS of the EGR upstream/downstream ports on the EGR tube. It looks like it.

It looks like one of the ports on his EGR tube is capped off. That should not be. It'll probably throw a code.