Anyone with a 1998 SOHC inside please

[baron4406]

Had no luck in the new person forum with this, plus I've been running searches for days to no avail. Ok I just bought my first Explorer (its about my 62nd vehicle tho) its a 1998 Eddie Bauer with the 4.0 SOHC. Has high miles (159k) but it runs great and everything works. Naturally there were a few issues, it has the 0174 and 0171 codes, cleaned the MAF and throttle body to no avail. Will be swapping the manifold o-rings when it gets warmer. This weekend its plugs, wires but first a Seafoam treatment. On to my problem, on my intake top there is the ISC, then right behind it there is a square plate with a rod sticking out about 1/4", behind that is a vacuum actuator with a rod that goes nowhere. It looks like these two should be connected in some way, however for the life of me I can't figure out how. Can't find any pics on here, my dad has an '02 Sport Trac but the intake is different. Can anyone help me with a pic or anything?? If you like I can take a pic, but on this site someone should know what this does. thanks

 

[mrboyle]

Post a pic if you can.

 

[jurick]

My engine has the same thing I forget whats its called but there should be a plastic piece on the end of the rod that slides over the rod sticking up and then there is supposed to be some type of snap ring I believe. Mine is missing the snap ring and I need to find a new one because the plastic piece keeps popping off of the rod. If I remember correctly it does something with the air over 3000Rpms. I was actually just looking at this in my manuel yesterday.

 

[IZwack]

I think thats the valve for the variable length intake.

 

[JohnnyBoy1102]

Dunno if mine has it but i can check the few under the hood pics i have to see what your talking about because i got a 98 with a 4 Liter V6 SOHC.

 

[JohnnyBoy1102]

now is this on the Air intake or are you talking about the intake manifold?im not very engine saavy so forgive my idiocy lol

 

[IZwack]

Here are some images I found of this vaccum actuated valve -- which I believe to be is the actuator for the variable length intake that opens at ~3000 RPM (which is the surge of power you feel at this RPM):

Images are from gold984by4's thread: http://www.explorerforum.com/forums/showpost.php?p=1470208&postcount=11

There exists at least two intake designs for the SOHC -- I think the other did not have this device on top.

 

[baron4406]

ah ok IZwack that's it. I assume the only place to get that little plastic is a dealer or junkyard. When I had other cars I could buy parts online from a diagram, but I can't find any for Ford parts. Any tips on where to find it?

 

[IZwack]

Contact the user KBABIAK -- he has a few Explorers for parts and he's somewhere in the mid-atlantic I think.

 

[4x4xbrian.com]

I lost that too!!!

I had the same problem, but I found it down under the plenum by the injectors... check, you may luck out too! when you get it don' forget to replace the c-clip or it just comes right back off.

best wishes

 

[EBInterceptor]

Maybe this repsonse is too late, but I haven't done any posting on this site in a while. The valve is designed to open up around 3,000 rpms. This allows the air to cross between the two plenums, and balance the pressure and get better flow of air. It would be like putting an H pipe on a true dual exhaust car.

 

[IZwack]

Maybe this repsonse is too late, but I haven't done any posting on this site in a while. The valve is designed to open up around 3,000 rpms. This allows the air to cross between the two plenums, and balance the pressure and get better flow of air. It would be like putting an H pipe on a true dual exhaust car.

I think this is beyond an "H" pipe in that this is a dynamic change.

The longer path at lower RPM takes advantage of Bernouli's principle from fluid dynamics in that a volume of air will travel at greater velocity if it encounters a path who's cross sectional area is smaller than the original. The greater velocity of air then means an increased in inertia per cubic volume of air entering the combustion chamber which leads to advantages such as fuel atomization (given the fact the air and fuel only have a fraction of a second to "mix"). The shorter path on the other hand typically has a larger cross sectional area and will therefore flow a greater volume of air at higher RPMs.

An "H" pipe is static and is not really based on Bernouli's principle.

 

[cybergasm]

Thank you Professer Iz

Damn i should have stayed at a Holiday Inn last night