Yeah, that threw me too (the black manifold). It's definately aluminium. The lower intake maniflod is black too. I've seen plenty of 91-94's in the junkyards and none have a black intake. Painted maybe??

I have the exhaust manifold from the 94. I'll just have to get the the one off my 91 and replace it when I get the EGR valve (I'm fabricating the piping).

Always tough removing manifolds.

 

Gil - you can't fabricate the piping from the exhaust to the EGR valve. Well maybe you can - not questiuoning your fabrication skills. But there is an oriface in the middle that provides a venturi so that differential pressure can be measured to then determine flow. Bernuolli (sp) principle - just like wings on an airplane. So unless you know the exact profile of the venturi/oriface, you're not going to get the proper pressure differential and then the right flow feedback to the PCM. You can see there are 2 tubes on the DPFE (differential pressure feedback EGR). One goes to the middle of the venturi and one upstream. Save youself the trouble and find a used one or buy it direct from Ford - I wonder if Napa would have it?

Huh - I thought the black intakes were plastic. Never saw one in person.

 

Thanks for the information. New unit is $156.00. EGR is $53.00. I'll buy a new EGR but $150.00 for a metal tube?

I have a used tube that is rusted off at each end (where it attaches to the manifold at one end and EGR at the other). If the venting near the two vacuum tubes is intact I think I could fabricate the tube extensions and threaded ends? Yes? No? I'll chop it up later this PM and check the condition.

Just for fun when I swap the manifolds I'll take a photo of both side-by-side so you can see the comparison.

Thanks for the posting. You have likely saved me a lot of time and trouble.

 

Yikes! those prices! OK then hack it off both ends. It doesn't matter how long or what shape the actual tube is as long as the venturi is the same.

 

You know what a picture is worth...



I have the 94 exhaust manifold. I need to weld in the adapter or buy a new one from FORD ($15.00) into the manifold so I can attach the EGR tube (notice the little adapter had been welded closed when this guy removed the emissions devices). I will remove the old EGR as it is rusted to s*** and replace with a new one. I have the DPFE (pictured detached) and the solenoid (not pictured). Notice the piping with the two vacuum pipes branching out. Is this the piece that has an internal valve? I was going to run pipe from one end to the exhaust manifold port and the other to a coupling on the EGR. Any problem doing that?

 

It's not a valve in there it's an orafice. Just like a venturi in a carburetor. Exhaust flows through it and speeds up inside the venturi. This causes a pressure drop inside the venturi. The DPFE sensor compares pressure in the tube to pressure in the venturi and measures the difference. (AKA differential pressure part of the DPFE) Simple physics P1V1 = P2V2 (pressure at point 1 X velocity at point 1 = pressure at point 2 X velocity at point 2) Since P1V1 is the reference and fixed at any given point in itme, and the venturi is smaller in diameter than the tube, gasses must speed up when going through it. For the formula to stay balanced, pressure must drop. This is how an airplane gets its lift. Air flows faster over the top of the wing and pressure on top drops. If perssure on bottom of wing is greater than perssure on top, the wing moves up, right?

So it doesn't matter how you attach the tube on the manifold or on the EGR valve. Obviously has to be leak tight. The original manifold fitting is a NPT thread. 1/2" or 3/4" I can't remember off hand. And since there is s fixed distance between the manifold and EGR valve once all installed, it would be a bitch to get a fixed EGR tube that actually fit. It was a pain getting mine back on with the new header since I think the header was off a little bit. I think then too that the tube OD is a standard tube size - 1/2" or 3/4". So I would think you could go to a hardware store and get new compression fittings to attach to th clean part of the tube, both sides, and then get some flexible copper tube with the right fittings on both the exhaust manifold and EGR sides. You know like the flexible Cu tube on the top of your water heater in the garage.

When all said and done, the 2 rubber hoses from the tube to the DPFE are a special silicon rubber with a higher heat rating. I think regular vacuum line will just melt. Check with Napa or the like and you'll need a few feet, depending upon where the tube ends up after your custom fab. I forget off hand which line is reference and venturi - the sensor is marked but at the tube end you can't mix them up or the PCM will see a negative flow, I guess is what would happen. I'll have to take a look under my hood and let you know. But at this point, I'd say I have a few days before you're ready for that.

 

Wait I just remembered the the two tubes to the DPFE are 2 different sizes. So I guess you can't get them mixed up. Good. I was afraid of opening my hood during the week. Like to restrict it to weekends only. And when am I going to learn to spell? My typing looks attrotious!

 

I had a look at the parts this afternoon. I sand-blasted the solid cast parts and took light sandpaper and steel wool to the tube. The manifold and connections will be fine but the steel tube has no integrity at all (spotty swiss-cheese). On the upside I managed to loosen all the manifold bolts from the 91 motor currently in the truck (which is a real bonus). The main stud bolts will come out easily as I only installed them when I swapped the motor last month.

It looks like $150.00 from FORD if NAPA can't help me. Probably a gasket set too (and EGR valve and coupler).

I bought the truck for $700.00 and the motor swap cost me about $100.00 for fasteners and gaskets and now a simple EGR doing me $300.00!! It's worth more than the truck!!

I'll probably get this done on the weekend.

P.S. you are correct about the tube diameters being different.

 

I forgot to mention this and it really depends how much of a hurry you are in but...There are online parts finders out there that you can make a request for a part and the request goes out to 20 or 50 or some number of wrecking yards. You'll get email response back from those who have it and what they want for it. You can also try eBay. I can't see paying that much for the tube.

I know what you mean about the manifold bolts. About 1/2 of mine I hade to cut the heads off with a dremel and then remove with a stud remover. When you reinstal, use a gasket. Fel Pro set for $6 at autozone. Stock was metal to metal but I guarentee it will leak if you try to reinstall without one.

 

Gil - this thread fell away. How did the EGR fix go, how did you make a new tube?

Any other "oh now what's" come up?

 

Time, time, time... I have none.

I did get the 1994 exhaust manifold onto the 91 motor (the port is capped right now). I just need to shell out the 200 bones for the parts and she should go together (I hope). I found a scrap 94 that I have been scavenging parts from so I have been upgrading other areas too (as you may have heard with the thread with TCMC on his/her CPM issues). I will need to replace the upper intake manifold (one off the scrap 94 with the EGR port) and all associated parts. No big deal.

I can't get the aspirator tube after market and if I find a wreck they are rusted to s***

I spent $700.00 for the truck, about $100.00 for fasteners/clamps/gaskets and now I have to go over $200.00 for a piece of tubing. Brutal.

It's my winter truck so I think I'll get the jobs comlete this month.

I'll keep you posted. Thanks for the help.

 

You seem like a fairly hands on, fabrication kind of guy. If your old tube is shot to hell, break it open and find out what they did to make an oriface on this thing. I've never seen one frm the inside. Would be a good picture. I guess yours is too far gone to even try to salvage then huh? Do a google or yahoo serach for "Explorer EGR Tube" and see what comes up. You should get a bunh of links to slvage yards. I've gotten up to 10 responses from different yards across the US with parts I've look for. I know there has to be some good ones out there. My tube has 171K miles on it and no rust whatsoever, a little on the NPT nuts maybe but that's it. I bet there's a bunch of them in CA.

 

Funny you should ask... I already cracked it open. Doesn't seem like much in there except a narrowing of the tube between the two vacuum ports. If I haven't thrown it out I'll get a photo. The whole unit was like swiss cheese so no luck there. It's dead.

I will try a search. Maybe I'll hit on something.

 

One of the vac lines has to be right at the smallest inner diameter. Has to for the differential pressure to work. I was just wondering what the cross section looked like - how they made the thing.

 

I bought the aspirator tube (new) today and installed the 1994 upper intake manifold. The EGR is new and I have installed the EVR, DPFE, IAC etc. All my engine wiring now has something to plug into, wow!!

Two questions:

The vacuum lines from the aspirator tube to the DPFE are just rubber vacuum lines, right? Nothing special except they need to be high heat? I see that there is a large diameter and small diameter on both the DPFE and the two aspirator tube ports. I assume these match up. According to Ford they have the same part number (for the tubing) so the tubing itself must be the same diameter. I assume the ports are sized to make ID easier. Just to be sure the lower port on the aspirator tube (closest to the exhaust manifold) is larger diameter and the upper tube (closest to the EGR) is smaller diameter. On the DPFE the larger port is "inside" closest to the intake manifold (ie. engine side) whereas the smaller diameter port is "outside" (ie. fire-wall side).

I now have two vacuum ports on the EVR (regulator) and one on the EGR valve. Any idea what the routing is for these three? My assumption is that one line goes from the EGR to one of the EVR ports and the other goes from (one of) the EVR ports to the vacuum tree. We can describe the EVR ports as "upper" and "lower".

Let me know if you can!!

Thanks.