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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

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!

1,874 Posts
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

1,874 Posts
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):

1,874 Posts
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!

1,874 Posts
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.

1,874 Posts
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).

1,874 Posts
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.

1,874 Posts
Discussion Starter · #28 ·
PM Seattle if you have any questions for him, your post will be deleted here.

From the forum rules:
Not trying to willy nilly and just go threw here and delete post or anything. But I have been putting an effort into keeping the Tech Write up section just that, A Write up section It Is to be used as a Reference if your doing the same thing/project.
There are rules for this area that no one/most don't follow, eg.Like If you have a ? You PM the original Poster. not keep posting in the thread. If You need or Feel you have to do that, Go Ask the ? in the noobie tech or the 80-96 tech section. more then likely you will even find the same ? posted many time there already. If anyone"original poster" feels that they just need to keep conversing in the thread ask And Ill move it for ya.

So a lot of threads are going to get cleaned up. Please be supportive of the rules for this area. Thank you All. Remember you all make this section what it is and it has some of the Best write ups of any forum out there.

1,874 Posts
Discussion Starter · #34 ·
My truck hasn't been driven all that much in the last 6 months or so since it's not a DD anymore, but so far everything has held up fine as far as I can tell. When I did my MAF swap I broke one of the vacuum Ts I used, but that was my fault.
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