2004 Ford Explorer 4.0 V-6 DIY tune up

Here's a few pictures of the parts I ordered prior to the job:

I got everything from Amazon in one box, free shipping for under a $100, including more dialetric grease and anti-seize grease than I'll need for quite a while.

Had the Explorer going on 7 years now. Bought it used with high mileage, off lease. Got a pretty good deal on it. Had to have the trans-axle (differential) rebuilt right after I bought it and I've had the transmission serviced. We've got 115,000 miles on it with about 78,000 on it when we bought it. Use it mainly for trips and to pull a small trailer. Good road car. Taking it on another trip in two weeks, thought it might be a good idea to tune it up, since I had no idea when it was tuned up in the past, if at all. Not running badly at all, just being proactive, and yeah it has enough miles to easily justify it. Looked a couple of Youtube videos which were talky and decided not to go through the wheel well but to remove the air feeder assy. to reveal the curb side (US) plugs (1-3). I decided to take a lot of pics to help me if I needed them and to help others who might decide to attempt it. The street side plugs (4-6) are the easy side. This addresses 1-3. If you can do those, you can do the others, using the same principles.

Curb side plugs are obscured by air intake plenum running from air cleaner to throttle body. We will remove the air cleaner cover and undo the rest, flip it over and place it in the air cleaner box.

Street side plugs should not be an issue to remove and replace. As you can see, if you have original equipment, the plug wires are all numbered. The replacement wires, from Ford, were not, but I used a Sharpie to put numbers on them.

Plug wires begin here and terminate at the plug. You squeeze the plastic pinch caps to remove them. I used dialectric grease on both ends of the new plug wires before attaching them. I do one plug at a time. Remove the plug wire, remove the plug, replace the plug wire, replace the plug. It's really hard to cross wire anything that way.

 

There are three plastic harnesses (top, middle of picture above) that the plug wires run through on the curb side. Each will need to be opened, retained and re-used. You just fiddle with one end of the clip with a screw driver (carefully) until it separates. Two of the harnesses are attached, the third is free standing. There are also two black, spiral, plastic wrap shields on selected areas of the plug wires which will need to be removed and replaced. The upper left of this photo shows one.

Unhook the air cleaner cover latches (2). Release the sensor plug (pull back on the red tab to release) and loosen the metal hose clamp by unscrewing it and then slipping it up and out of the tab on the side. I spray everything with a soap and water solution to make it slippery. You can pull the rubber up a bit with a screwdriver and squirt some soapy water to make it easier to slide on and off. Use to remove and replace.

I use old plastic squirt bottles that are left over. Squirt it a few drops of Dawn (or similar) and fill with water and shake. I have them all over the shop for removing bicycle and motorcycle hand grips, etc., etc. It also works to clean your hands after GoJo. Don't completely unscrew it, only enough to allow it to be removed for later.

 

 

 

Set the air cleaner assy. off to the side for later.

I ordered an air cleaner when I ordered the plugs and wires. As you can see from my Sharpie lettering, it's time to replace. Go ahead and remove the filter, we are going to use the space for temporary storage soon.

Pull air sensor hose off the 2nd fresh air plenum.

 

Unscrew the hose clamp and release it from the throttle body intake.

 

There are still attachments to the intake hose but we are going to flip it over, back to front, inverting it and we will place it in the air filter box, out of the way.

Here it is inverted and still attached on the underside.

It's now placed in the air cleaner box, out of our way.

Two and three are now revealed for replacement. Unfortunately we're going to need to remove a bracket that is near plug one to make replacing the plug wires easier. The good news is it isn't hard to remove.

Here's the metal bracket straddling plug one. On the right side bottom is a 15mm bolt and on the left side is a 10mm bolt. Remove both bolts and flip the bracket up and out of the way with it's hose still attached. Also note the position of one of the two black plastic shields. This one we will need to transfer over to the new #1 plug wire. You can also see the plastic harness which will need to be opened. Note how the plug wires run through the harness.

 

 

 

Here's the same area with the bracket moved up and over the top of the area and out of the way. You can see the two shiney metal threaded areas above the exhaust manifold that the 15mm bolt (right) and the 10mm bolt (left) resided prior to removal. We can now get to #1 a lot easier and we can thread the plug wires to and from the plugs without the bracket's interference.

Here's the bracket with hose temporarily placed up top and out of the way.

I did #2, #3 and #1, one at a time so I can't cross wire anything. The plugs are at an odd angle. Mine were tight. Pulling the plug wires off is a chore. I separated one and had to use pliers to remove the metal plug clip which was shoved on so hard it was bent. I had various lengths of 1/2 and 3/8 extensions and wrenches to do the job. I have three plug sockets and the smallest one was used here, like most modern plugs, it is pretty small. As you can see I needed to use a torque wrench to free up one of the plugs. They were tight. Go easy and keep the right angle and use more extension rather than bang on it. I wish I could say it was easy. It could be but it depends on how long the plugs have been in there and if any anti-seize was used (we will use it to install our plugs)

 

The old plugs weren't bad. Probably had a tune up before I bought it. I replaced the old Autolite platinums with new Autolite Irdiums. The plugs are gapped in the box and I eyeball them to make sure they haven't been dropped. If you're anal, you can use a gage. I think they're .054. Undoubtedly the old ones are wider and worn a bit, which is to be expected and why they are replaced. You see the rusting on the threads is why I had such a hard time breaking them loose. If you don't have a cheater bar, you may struggle to get them out. Hand thread the new ones in with anti-seize on the threads and snug them up with a normal sized 3/8 wrench. Overtighening breaks the ceramic insulators. Put the conductive grease on both ends of the plug wires before installing.

Here's the new wires with my Sharpie number markings. The metal bracket will go back over the number one plug wire after you've threaded all the plug wires through the area.

New air filter with date, courtesy of our Sharpie.

Putting it back together is reversing the disassembly steps. Just remember to use soapy water on the hoses to make them slide together easier and reattach everything you removed.

 

Plugs and wires 4,5 and 6 will be a breeze after doing 1, 2 and 3.

You will not have a hard time if you have adequte tools and some experience in doing plugs and wires before and you have patience and don't hurry. If you're a decent shade tree mechanic, it won't be hard at all. Expect to be frustrated if this is your first mechanical job but perserverance (& good tools and arm strength) will see you through. Just remember to do each plug and wire one at a time and hand thread the plugs (with anti-seize grease on the threads) back in before using a wrench. Double check your job. Pull on each installed plug wire you've put on to make sure they don't just pop back off. Push and pull multiple times to be sure they're seated properly. Recheck each harness to make sure the wires are running through the looms as they should. Make sure you've put the black coiled shields back in the right places. Your Explorer will run better and your fuel mileage should improve.