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Discussion Starter #1 (Edited by Moderator)
This should cover most 87-96 V8s (302\351); for the I6s (300)s the solenoids are in the same general
area, as well as the valves. You can use this article as a basis to replace yours, just keep in mind it
will be slightly different.

Parts you'll need:
All available from a local autoparts store (except one)
Approximately 20' of vacuum hose (5\32")
2 Vacuum T's
Patience

To get started, I'll explain what the point of it all is. The EEC (Electronic Engine Control or computer)
uses electronic solenoids to send vacuum to valves (in this case, three valves: the EGR, the TAB
(next to the SMOG pump), and the TAD (behind the upper intake plenum). The EEC sends a
signal to the solenoid and it "opens" the valve to allow the engine vacuum through.
The easiest way to understand this is with the EGR.

At idle, the EGR is normally closed; but when you get to highway speeds, the EEC wants the EGR
to open. The EEC sends the signal to "open" the valve to let the vacuum through and the
vacuum opens the EGR. For a more in depth description of the TAB\TAD systems,
see this post (Thanks WuTang).

The TAB valve works the same way, it either directs the air pumped from the smog pump onward to
the TAD valve (we'll get there) or out to nowhere (not used). When the TAB valve directs the air
onto the TAD valve, the TAD valve either directs the air from the smog pump down into the catalytic
converter, or into the back of the engine. Here's a pic:



You can see the coil, the TAD, TAB, and EVR solenoids (EVR controls the EGR). You can see
the yellow line coming from the TAD solenoid, the pink line coming from the TAB solenoid, and the line
coming from the EVR is green; can't see it, but it's there. What you can't see (but when you look
at your truck you can) are the vacuum hoses that plug into the bottom of the solenoids. This is
where the vacuum is supplied to the solenoids. On the EVR(EGR) solenoid, it goes straight to the
vacuum tree (vacuum hook-up on the intake manifold). On the EVR(EGR), the top (green)
hose goes straight to the EGR valve, and the Bottom (red) hose goes straight to the intake manifold.

The TAB\TAD valves are a little different, but not much. The only difference is that the red line
(yes, the exact same one that goes to the bottom of the EVR\EGR solenoid) goes all the way over
to the vacuum canister on the fender, the vacuum canister stores vacuum for these valves
(TAB, TAD). Then there is a black vacuum line coming out of the vacuum canister next to the
red line that goes all the way back over to the bottom ports of the TAD\TAB solenoids.
From the top of the TAB solenoid a pink hose is run to the valve right next to the smog pump
(I'll show a pic after this rambling paragraph). From the TAD, there's a yellow hose run to
the TAD valve behind the intake manifold.

Here's a pic of a motor that's pulled, just so you can see where the valves are and such;
but you don't have to pull the motor, lord knows I didn't.




You can see the yellow line going to the "diverter" valve (TAD). You can also see
the “bypass” valve (TAB) (you can't see the vacuum line going there, but when you
look at it on your truck you'll see it), plus the EGR and all that other stuff.

Ok, so now that we have an idea of what goes on, let's get started. To avoid confusion,
only run one hose at a time. We need to replace\rerun the red vacuum line, so take a
piece of vacuum hose and run it from the vacuum tree on the intake manifold to
the vacuum canister.

Run it around the back of the engine (I ran it on top of the passenger side valve cover,
under the upper intake plenum). Plug the hose into the vacuum canister where the red
hose plugged into. Here's an overhead pic of how I have my vacuum lines run, you can
also use this to see how to run new (rubber) lines to the FPR (Fuel Pressure Regulator)
and the MAP (Manifold Absolute Pressure) Sensor. In all my pics I tried to use the most
sophisticated graphic design program known to man (Paint) to help. I tried to keep the
coloring the same as the original colors, with the exception of the MAP sensor and FPR:



Go back to the driver side of the intake, where the solenoids are, and cut the vacuum line
you just ran so you can put a "T" on it and run a very short vacuum line to the bottom of
the EVR\EGR solenoid:



From the T you connect a short vacuum hose to the bottom of the EVR solenoid, Pic:



Then run a vacuum hose from the top of the EVR solenoid where the green line used to be
(see pic above) to your EGR valve. I ran the hose through the hole in the middle of the
intake plenum, and then ran it up to the EGR:



Now go back to the vacuum canister, and run a vacuum hose from the OTHER plug on the
canister(formerly black line) to the bottom port on the 2 solenoids for TAB\TAD. You will
need another "T" so that you can split the hose into 2 hoses, one for each solenoid.
Kind of hard to see in this pic, you can see the white tip of the T, but it'll make sense
when your doing it:



2 hoses coming from the vacuum canister (A.C. stands for After Canister):



After that, run a hose from the top port on the TAD (front of the 2 solenoids) to the diverter
valve behind the intake plenum (originally it was a yellow hose). Here's a pic, I literally
set my camera on the intake plenum, and took a picture behind it; so it's kind of close up:



Almost done!
All that's left is to run a vacuum hose from the top port of the rear-most solenoid (TAB)
to the valve that’s right by the smog pump. This was the hardest part for me, but I have
fat fingers, and truthfully it wasn't that bad; just annoying. Here's a pic, it might be easier
to plug the hose in from under the truck, but I was able to do it from the top.




Here's the solenoids with the TAD, TAB, and the A.C. (After Canister) line:


That’s it for the SMOG stuff, but if you want to completely do away with all the plastic crap,
you can run a new hose from the vacuum tree straight to the FPR (fuel pressure regulator),
as well as a vacuum hose straight from the vacuum tree to the MAP sensor.
Here's some pics of the whole set up, you can see the hoses going to the solenoids:



If you change out the FPR and the MAP hoses, then you can literally take out the plastic
crap so it doesn't clutter up your engine bay, like I did:



That's pretty much it, now you have a rubber vacuum system!

Thanks goes to WuTang for proofreading\ideas, and thanks to Miesk5 for clarification on what
years this applies to and his never-ending knowledge!
 

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Discussion Starter #2
If you want to color code the hoses, heatshrink is a good idea, but I could see it being a pain; unless you just do the ends of the hose, then go for it. I know I've seen a pack of colored electrical tape (has like 8 rolls, each a different color) at Lowes\Home Depot\Harbor Freight; one of them, they all kind of blur together lately lol. Maybe you could use that to wrap the hoses, too. Both would work great to color code it.

As far as reliability, I've had these hoses run this way since December with no issues. I was somewhat worried about the EGR tube thats under the intake plenum, so I kept an eye on that for awhile, but no problems at all. My plastic hoses were leaking and I didn't even know it; I touched the TAB line when I was changing the spark plug wire and it snapped; IIRC, might have been somethin else I was working on but I just caressed it and it broke. Sound familiar WuTang? :haha
 

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Yep it sure does, lemme see if I can find a pic of the solenoid online. Also lemme see if I can find a non-colored pic.

You can see the hoses on the inlet\outlet of the EVR solenoid here:


Here's a drawing\breakdown of the EVR solenoid (the TAB\TAD are basically the same):
 

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I made an easy to understand diagram on an excel spreadsheet if anyone needs that may help as well. anyone needs it let me know

Booba, why are you running your plug wires like that ? I am guessing 7 and 8 ? does that hlep to avoid crossfire
 

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Discussion Starter #5
Yep I did it because my new valve covers didn't have the fingers built on and at the time my plug wires were new so they kept coiling over and sitting on each other. So, to be safe I ran it that way. Works like a charm!
 

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I went out this morning and spent $20.00 on the 5/32 rubber hose, before I looked under the hood, to find the rubber hose I put on there last year dried out, and was broken. I think this rubber hose at the least needs to be wrapped in wire protector to keep the heat from getting to it. Napa still carries the replacement plastic tubing, at like 3 times the price of rubber hose. The tubing also is not barbed at the ends, and only comes in 12" sections.
Good idea.

There are some points that loom would make sense. I'll look mine over and see what I come up with. If nobody comes up with with something before I get a chance to loom it all up, I'll post pics of what I did.
 

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Discussion Starter #7
That's why I ran it up by the valve covers, its away from the exhaust and such. 2500 miles with no problems so far.
 

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Discussion Starter #8
These diagrams and pictures are all if the same stock setup, yellow goes to the diverter valve(behind the intake), pink goes to the bypass valve(behind the smog pump).
 

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Thanks Booba5185! You motivated me to replace my old plastic vacuum lines with new Silicone lines and eliminate those pesky vacuum leaks! Your thread made it easy.

Replaced the Emmisions Solenoid lines...



Through the Edelbrock Intake Manifold...



Protected with Wire Loom...



Out the passenger side...



Plus a new Air Tube Adapter...



Found a vacuum leak!!!



See the pin hole at the top?



Patched it with Blue RTV and a plastic patch...



Then swapped it with the good Cruise Control VRESER for good measure...



I found the Cruise Control diaphram was leaking as well and temporarily capped it...



All is good now. Thanks again Booba!!!
 

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www.siliconeintakes.com


Get the Silicone Boost/Vacuum Hose Engine Dress Up Kit and then an additional 10' of 4mm vacuum hose in the color of your choice. I used wire loom to protect the hose through the Intake Manifold, to the Diverter Valve and where it rubs on the Intake to the EVP. :thumbup
 

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I ended up finding 4mm silicone hose on eBay right after I posted that. I ordered 13 feet for 11 bucks which includes shipping.. i got blue so I can match you hahah. I also have wire loom already so I'm good to go... this is a cool idea. My plastic vacuum lines are royally fawked. Three are snapped completly in half


I'm actually second guessing the ebay stuff now that I read the silicone intake site. Think ill be ok with the thin stuff? It's 0.100 wall thickness
I tend to use quality components direct from manufacturers and avoid the unknowns of eBay. The thing with Silicone Lines is they tend to be soft and at the mercy of sharp objects but additional thickness of SiliconeIntakes.com vacuum lines provide resistance to cuts and vacuum collapse. Please let me know how your vacuum lines work out and any measures undertaken to protect them.



Ok, I will check the IAC and PCV valve. But, the vacuum lines don't hook into either of those parts. Let me recap: Bronco wasn't running great with some broken vacuum lines but no idle fluctuation and it wouldn't die when you turned on the A/C. I replaced all the vacuum lines and now it dies when I turn on the A/C and at idle it revs up and down. Could this be a problem with an emission part or solenoid that had a broken line previously and now it is causing problems because it is hooked up?
I found a vacuum leak in my VRESER (Vacuum Reservoir) and in the Cruise Control Diaphram. Check vacuum in these along with your Emissions Solenoids (TAB, TAD, EVR) and EVP & EGR. The use of a hand vacuum pump can isolate leaks and aid in testing components.

FYI, there are two (2) VRESER in non-electronic/vacuum controlled Cruise Control Broncos, such as my 1990. One on the passenger side is for Emmissions Solenoids and TAB/TAD Valve vacuum and one under the Coolant Overflow is for Cruise Control vacuum. Look in either wheel well for two retaining nuts. Remove them and the VRESER (Coffee Can) will simply pull out of the top. Examine them very closely and test with a hand held vacuum pump. These will frequently rust underneith or have pinhole leaks especially in older Broncos.

After isolating my vacuum leaks, I changed my spark plugs and replaced the EVR yesterday. Currently no codes, 19 inHG at idle and 11 inHG at throttle. Today I drove 100 miles at 12.5 mpg. A big change from the usual 9.5 mpg... :twotu:

My Engine sounds a whole lot smoother, a noticeable pause on initial acceleration is gone and it is definitely more peppy and "wants" to run. The old spark plugs read very good considering I have ran them in the new engine for the past year with a recently corrected TFI ICM issue. Funny, because I thought fixing a lean condition would be just the opposite... :scratchhe

Anyway, definitely check the IAC and PCV. Also, get a hand held vacuum tester and isolate/check different areas of your vacuum system. It's easy, it's fun and it's invaluable information... :thumbup


 

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Ron (seattleFSB), for those of us too lazy to go outside and remove and measure... what size/type of hose did you use for the intake tube? Hump/straight/reducer?
I will post this in another Technical Write Up as I do not want to monopolize Booba5185's excellent thread, (like I may have already done). Sorry Booba... :beer

Adapting a K&N Air Tube for MAF Upgrade
 

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It's a one-way vacuum line that comes from the vacuum tree and branches off twice to the HVAC. I did not replace the second line as it goes through the firewall.

I believe that the line at the top of the first photo you are refering to goes to the blend door. The second photo shows the harness where the lower line enters through the firewall.








On anther note, how do you bend your thumb back that far? Now that is cool... :twotu:
 

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Here is a quote from miesk5:


yo, Yes... Get a vac canister back in there.
The vacuum reservoir is just what its name implies, a storage device for vacuum. The engine creates vacuum. The vacuum is an energy that is used as a power source to operate different emission controls and accessories like the controls for the ventilation system. There are times that an engine does not create a good supply of vacuum. Because of this the vehicle manufacturers install reservoirs to store vacuum. The hose from the engine or the reservoir itself will have a check valve that blocks the loss of vacuum back to the engine. Why is this? When accelerating, the amount of vacuum created by the engine drops to a level that will no longer power any emission controls or provide for control of the ventilation system. The reservoir is designed to hold enough vacuum in storage to maintain control under most driving conditions. If the check valve fails the vacuum reservoir will lose vacuum so quickly that there will be none left in reserve. The result? A loss of control of vacuum operated devices.

You can make your own as SigEp did but for the Emission stuff
Fabrication in a 95
Source: by SigEpBlue (Steve) at http://www.fullsizebronco.com/forum/showthread.php?t=131448

GL!
 

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Discussion Starter #17
Maybe an hour or two, depending upon how detailed you are. Not a pain, sort of fun actually.

Be sure to have the proper sized tees before you start. When you pull the old harness, be sure that you remember where all of the lines go. Climb up on the driver's side engine with a flashlight to visually see where the TAD line goes. Feel for the PCV tube on the passenger side rear upper intake.

Run all of your lines one-by-one to ensure that they go to the correct location, or better yet mark them with tape. I recommend that you use inexpensive wire loom to protect the lines through the upper intake manifold or other heat areas. Cut all of your wire loom pieces together so they are the exact same length for a finished appearance.

While you are at it, access the Vacuum Reservior mounting bolts from under the wheel well and remove it to inspect for holes or leaks. Using a vacuum tester is advised for the reservoir and all of the new lines.
sounds about right, maybe a little longer. I did mine while I was replacing my injectors and such, so its hard to say how long it took.
 

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Replacing vacuum lines

This thread was very informative. I took a slight twist to the concept and replaced the vacuum lines with brake line that can be bent to fit using simple hand tools. I cut off the factory ends which were set up for compression fittings and used the same rubber hose on each end to connect to each sensor/valve. Crazy glue does a great job sealing the hose to the brake line. The other end just slips over the sensor/valve. I even painted the lines to match factory colors so I don't get mixed up. You couldn't tell the difference unless you reach in and touch them. These lines should hold up very well to heat. I found it best to remove the upper intake to dry fit the lines.
 

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Wow excellent write up Brother don't know how missed this, so I shouldn't have any problem doing this to my 86 EFI.........?

I notice the OEM plastic and rubber vaccum lines on mine some appear to be different sizes or is that an illusion, difference in materials etc.....?

I think I'd go with the RED lines, it sure does look nice, are the silicone lines hard or soft.........and I'm getting that with all new vaccum lines performance is better.......?

Do the Tee's come with the lines or do you have to buy them else where.........? Cost...?

I think it's time for this upgarde on my BKO and it looks easy and fun........

I've been using tie-wraps as "bridging clamps" for repairs on my lines .....simple, works great, makes a good seal and they're not expensive!

Thanks ~ :thumbup
 

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Thank you guys for an excellent thread. I'm about to order away, and just wanted to clarify a couple of things so I can get quantities accurate:

1. Do the quantities of 4mm / 5/32" hose you guys are talking about include replacing all of the plastic HVAC vacuum hose going through the firewall as well as throughout the dashboard? Or are you guys only replacing engine and emissions related plastic hose? I ask because my interior plastic hose looks like they're in great shape and my vent dampers are working fine, so as long as the one-way check valve isolates any possible leaks on the HVAC side I'd rather not replace the HVAC hoses right now.
See the parts list posted by Booba for rubber lines and myself for silicone lines. Not including dash HVAC.




2. Is it definitely unnecessary to 'clamp' the ends of vacuum hoses onto barbed male fittings? Not sure what to use, but it seems like it would be simple insurance to keep hoses in place and sealed.
No clamps required as they are flexible and fit tight on the sensors and tees. Tees are cheap and usually come in a package of several. Look at the pics again.
 
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