Explorer vacuum lines (the thread to end all threads)

1buckeyefan1 said:

So most of the threads i've read suggest capping all but 3 vacuum ports:

1.) Positive Crankcase Ventilation. However, the explorer actually uses two ports. I'd like to learn more why?
Answer: Because Engineers choose between alternatives, and compromise between designs. The PCV system has been a source of evolution in the Ford world since at least 1967. If you look at a 67 Ford 390 GT in the Mustang, you will find a giant balance tube and a half a dozen fittings between the front and rear intake runner...that has a big TEE in the middle that goes to the PCV valve. If you have a Ford, and you lower the hood line...then the ideal location in plenum below the carburetor becomes unavailable. I am sure that some engineer in the engine group said "fine...If you are going to create a huge vacuum leak in the intake manifold, the least you can do is balance the leak across both banks." and so the external balance tube was applied. You see it in the 67 Mustang with the FE. Not in the truck, or full size...but anything with a low hoodline. It's a really stupid compromise. It trades a lot of external plumbing for practically zero benefit. The vacuum leak is only relevant at idle. The explorer rubber hoses become brittle, leak, fall off, and look like crap. If you can pull from the center plenum area then you only need one port. Otherwise, you should use 8 ports, and build a giant manifold with hoses that are at least 2 feet long from each cylinder. You can see that Ford is trying to do that with the "two ports as far away as possible so as to reduce the variation on the PCV inlet..." design.
2.) Fuel Pulse Damper (FPD), sometimes referred to as a Fuel Pressure Regulator
Yep, you need this. As far away from the aforementioned giant vacuum leak (PCV) as possible.
3.) Brake booster
You also need this. Also as far from the Giant Vacuum Leak (PCV) as possible.

So I have attached a picture of my upper intake and have labeled everything 1-8. I'd love it if the gurus can help me identify what they were all intended for before I start plugging them?

1.) PCV #1 - runs into a F-type tubing system. This is mated with #5. BroncoBowsher had a really good explanation on how the PCV 'plumbing' works a few years ago:

The PCV on the bottom is actually a neat piece of engineering. There are 2 fitting (front and rear) at the very bottom of the intake. The lines Tee together before going into the PCV. This was all done with a purpose. If you get any fluid into the intake (blowby, water splashed in) it can settle at the bottom of the plenum. When the engine is shut off gravity will drain it down and dump it into the crankcase via the PCV. Look at the lines as built by the factory and they have a downward slope to them.

This was done for a reason, and I have seen it happen on other engines. If the liquid accumulates enough it can start to pour into the rear most cylinder. Better to have the oil drain back into the crankcase. Even a little water is no big deal in the crankcase (heat will vaporize it). The one I know really killed an engine was a hard run and the second stage of the intake opened, running a slug of fluid into the cylinder at speed.
Ford engineered a drain for a reason, I made sure to keep it.

https://classicbroncos.com/forums/showpost.php?p=3138415&postcount=11

My question is.. why not simply retain both ports for PCV and use the Explorer tubing system? Why are most folks only leaving 1 port for PCV?

The above answer is nonsense. The lower port in the same location on the 1993 Ford 5.0 EFI Cobra has those ports plugged. I'm not saying that some clever engineering didn't take place...but the engineering that took place happened AFTER the decision to implement the multiple vacuum locations.

2.) Brake booster. Unless you're running Hydroboost, you'll probably want to keep this.
Keep it anyway. It doesn't hurt anything, and since you have to plug it...plug it at the end.

3.) Fuel Pulse Dampener (FPD) - looks like most folks refer to this as a Fuel Pressure Regulator. I plan to keep this, but need to figure out how to plug the extra port that goes to the EGR that was shared with? (see pic) Once again, BroncoBowsher had an excellent explanation on what this is for a few years back:

The retrunless also adds a pulse damper to the fuel rail. It is the thing that looks like a fuel pressure regulator but isn't. What it does is act as an accumulater so when an injector fires the whole mass of the fuel in the fuel line doesn't have to start moving. Also when the injector stops it acts as a bumper so the fuel pressure doesn't hammer the system.

Why returnless? There is a little cost savings in only running 1 fuel line, also less potential for leaks. But the biggy is emissions. A return style dumps hot fuel back into the tank. That wants to vent as vapor. If you keep the tank cooler it is easier to control evaporative emissions. We did a lot of testing of this stuff back in that time frame.
Nice explanation, but again...doesn't apply here. The FPR port is the Fuel Pressure Regulator Port whether you have a pressure regulator or not. It was the FPR port in 1986, and it gets to keep the name. The fact that you use the same vacuum signal for the Fuel Damper is kind of irrelevant. It just helps to ID the port. It's a manifold vacuum port, and if you call it the FPR port...99% of mechanics will know what you are talking about. You can also call it the "original FPR port that was repurposed to the Fuel Damper Port but may or may not be used..."

4.) I honestly don't remember what this was for. It has a 90deg plastic fitting at the front (pic attached). Can't find many references to it. Help?

5.) PCV #2 - as mentioned above, I plan to retain this. Although my PCV tubing broke, someone is selling NOS replacements for <$20 on ebay and I have one on the way.
Yeah...don't. There's a reason why your original broke. It's because they suck, and you don't need it.

6.) coolant line #1 - I've read that most people cap this off, along with #7 (and run a loop as pictured below). Best I can tell/read, Ford engineered these to flow through the upper intake as sort of a preheat/deicer? My real question is if why abandon this and rather than simply looping the 1/4" on the heating lines, why not just connect them?

Wow...really? The EGR coolant passages that prevent the hot exhaust gasses from melting the aluminum intake parts? The one's that provide a small amount of continuous coolant flow so that the sensors that are immersed in the heater tubes can actually measure the correct temperature, and are therefore necessary even when EGR is deleted?
7.) coolant line #2 - same as #6

Don't forget that every since those folks froze to death in that snowbank...all heaters in passenger cars must have coolant flowing in the heater core at all times. So by 1977, the heater water flow control valve was pretty much obsolete. Now the temperature is controlled by a blend door. Thus, if you connect to a "full flow" heater core...you don't need to loop the coolant hose. But if you connect to a heater core that has a water shut off valve...then you need to find a way to create flow in the tubes to keep the sensors accurate.

8.) I don't remember what this was used for as well?
I appreciate any feedback y'all might have. Hopefully this consolidated info will help others.

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jamesroney said:

Lots of opinion in my post...I hope you find it useful.

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1buckeyefan1 said:

Absolutely, thanks for chiming in. I really used all of your feedback in designing my fuel line and in-tank EFI plumbing.. glad you provided your feedback there and here.

Let me try to summarize (again, going off my labeled picture)

1.) PCV - one is needed (#1), the Explorer F-type plumbing isn't really necessary? I really appreciate the historic lookback.. that's what I was really looking for.. how it has evolved.
Yes. but I would go PCV off of #5 if you subscribe to the scavenging of the upper plenum.
2.) Brake Booster - keep it, (or cap it, even if running hydroboost)
Yep. Keep it, AND cap it.
3.) FPR port - keep it, and hook up to dampener
Yup.
4.) Still a mystery port, i'll keep digging
5.) PCV #2 - seems unnecessary if not retaining the original Explorer plumbing?
See #1.
6-7.) just a route that keeps coolant on the sensors for proper measurement? So why go-to a short loop vs. the long loop through the upper intake
That's not strictly true. It was not intended to enable the sensors. It was intended to cool the EGR. But since you have no coolant flow to the heater core...you need something.
So it all depends on where you put your ECT sensor. Since the temp sender takes up the only available port in the water jacket...you have to put the ECT somewhere. I have found that it measures adequately if it's just stuck in the fitting. My goal is to keep it clean and simple.
8.) still unknown, I'll keep digging
I thought this went to the EVAP purge solenoid.

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904Bronco said:

Original Ford part, still available, and the only thing they will sell you since earlier Explorer part no's are obsolete.

#4 vaccum for fuel system purge.

Small 1/4" cooling lines - At minimum they allow coolant to move in the tubes when the heater control valve (Explorer) was closed so the ECT would provide a correct read on coolant temps. 1996-97 there was just a straight piece of hose between the two as they were placed differently on the coolant tubes. Later years had lines that ran to the upper plenum to aide in warm up - colder climates. I think it was Tasker who posted up a picture of the current Ford replacement cooling tubes. Those don't have the tubes/ports for the warming feature, but there is a loop between the large tubes built in.

Personally I like retaining the Ford features - keep the plenum preheat tubes but to silicon hoses. And EGR. At minimum loop the two ports together as shown in above picture.
Ports I am not going to use, I remove and tap holes for threaded plugs.

Here is a picture of my 96 Explorer/Mustang Hybrid.

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jmhend said:

I don’t recall seeing a picture of your lower intake but wanted to ask what you did for the ACT port.

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1buckeyefan1 said:

Saw your other post.. I'm pretty sure my ACT is over in the MAF part of the intake (2001). I've seen a few posts on how to keep it there, just haven't made it that far yet.

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1buckeyefan1 said:

Saw your other post.. I'm pretty sure my ACT is over in the MAF part of the intake (2001). I've seen a few posts on how to keep it there, just haven't made it that far yet.

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fordguy said:

Buckeye, how are you going to plug the egr part of the fuel pressure reg. Plug View attachment 918466 View attachment 918467

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1buckeyefan1 said:

are you referring to the extra white line that goes into the elbow w/ the double hole? It's been a little while, but I believe i simply pulled the white line out and then plugged the hole with a plastic plug.

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