This is really several repair jobs rolled into one.
What started it all is that packrats chewed up the wires to all three fuel injectors for the rear cylinders. Amazingly the car runs on 3 cylinders, at least well enough to move it 40 feet or so to where I want to work on it. The wires in question are in the rear, and there is no way to work on them without removing the intake manifold.
So, I am going to do the following in one big job:
Since the intake manifold needs to come off, this seems like a good time to do the valve cover gaskets. And only a fool would have the rear plugs nicely exposed and not replace them. And along with that, the old plug wires are crumbling away, so we may as well replace those also.
Whenever possible (i.e. always), I thread bolts and nuts back onto the studs or holes they came from as soon as a part is removed. This saves all kinds of confusion when things go back together.
One great thing about working on Toyotas, is you need just a 10, 12, and 14mm socket to do almost everything.
Removing the back seat gives access to the fuel pump. The seat comes up without any tools, just get a good grip on each side and yank straight up. Once the seat is loose just maneuver it out of the way. A circular cover with a cable passing through it is the fuel pump access hatch. The idea here is that to relieve the pressure in the fuel injector lines, you open the hatch, disconnect the fuel pump connector, then run the engine until it dies. The problem here is that the hatch is glued in place. Could there be a better way? Like a fuse?
I pried open the hatch, carefully unmated the connector, and tried to start the engine. I would not even start. Apparently my vehicle had been sitting long enough for the pressure to leak out and all of this was unnecessary. A friend said that when he worked on his vehicle, he skipped all of this and was just careful when he first disconnected lines with fuel pressure. So I remate the connector, and reseal the hatch. The tar or whatever it is is plenty sticky enough to just press it down again.
Once this exercise is finished, disconnect the negative battery terminal
Disconnect intake air temperature sensor cable. This connects to the big plastic housing over the air cleaner. There is a small vacum line and a spring thing also connecting to this housing. Release the 4 clips that hold the air cleaner housing. Disconnect another larger house that connects to this at the lower rear and remove this housing.
Another large plastic thing is connected behind this. Disconnect one hose (rather petrified) that goes to the front valve cover and remove this.
Two 10mm bolts hold the bracket with the accelerator and throttle cables. Remove these bolts, disconnect a spring and get this bracket out of the way along with its cables.
Three electrical connectors can be removed from the throttle body. Use care with brittle plastic.
Disconnect three hoses at the lower rear of the throttle body. The way I did this there was one hose that connected to a black plastic box in the middle of some hose. (This is a vacuum line.) I left this hose attached to the throttle body. The other two lines are coolant lines. The leftmost hose comes from high on the engine, I disconnect this at the throttle body. The rightmost host comes from low on the engine. I also disconnected this at the throttle body.
My throttle body has two bolts on top, two nuts on bottom. Hence it is a type B. All are 12mm, Remove these and remove the throttle body. The lower left bolt holds a bracket with one of the electrical connectors. It stays behind when the throttle body comes off.
Remove upper radiator hose.
Disconnect 3 front spark plug wires. The brittle plastic snap tabs break and crumble when I do this. One 10mm bolt holds this bundle of wires. Move these wires out of the way to the left.
Disconnect a harness with a myriad of connectors and move it out of the way to the left also.
Two 10mm nuts hold a vacuum manifold. Disconnect a number of hoses, leave a big stubborn one attached and move this out of the way to the right.
At the passenger side of the manifold is a can like part of the manifold. At the lower left corner of this is a nut holding two ground wires. Remove this nut and release the wires.
Behind this, between the "can" and the firewall is a very hard to get at 14mm bolt that anchors a reinforcing strut with a hook that looks like it is part of the scheme to lift the engine out of the car. This bolt must come out, which would not be so bad, but some very stiff hose is in the way. (It turns out this is a power steering hose, and is attached to the brace by a 10mm nut, just an inch or so right of this troublesome 14mm nut. If this 10mm nut is removed, the stiff hose can be moved back, making this much easier.
Once this is out, it is quick work to remove the intake manifold. An 8mm allen key removes two bolts at the front, and a 14mm socket removes two nuts at each side. There is a hose at the passenger side to disconnect, (the PCV hose) and one at the driver side that goes to the brake booster. One last ground wire at the rear must be disconnected. Now the intake manifold can be lifted off. I covered the exposed holes with masking tape to prevent debris from entering the cylinders. I laid the gasket on top of the taped holes hoping it won't get damaged.
All of this was an afternoons work for me.
Remove the three rear spark plug wires. They pull straight up, but were pretty tight and well stuck. The entire plug wire harness can be removed.
Remove two 10mm nuts holding wire harness over rear valve cover.
Remove two convenient connectors from this harness on the passenger side. Another connector is down low behind engine and awkward, remove it also.
3 12mm bolts hold the Y-shaped bracket to the "dogbone" engine mount brace. These bolts and bracket need to be removed to allow the wiring harness to be lifted off of the valve cover.
The EGR tube can be removed via two 10mm nuts. I had hoped this could just stay on, but it prevents access to one of the nuts holding the wiring harness, so off it comes -- not all that hard.
Three 10mm nuts hold down the wiring harness on the driver side.
Two connectors on driver side, one up top is easy. The one behind the engine is very tricky. The first thing to know is that the top is anchored. The bottom part pulls down and loose, which is the big surprise. The top part can then be popped loose from the anchor on the metal bracket. I simply broke it, but without damaging the wires -- which is the main thing. I will tie wrap it back on later during reassembly.
On the passenger side is a connector in a box labelled "diagnostic". This and the round "holder" below it can be released by pulling at plastic tab away from the metal bracket. The important thing is to release the "holder" to give some slack to lift the wiring harness.
Now the harness can be wrestled up and away from the valve cover. Unfortunately it cannot be just pivoted away entirely without a lot more work, but it can be maneuvered back and away to give enough clearance to work on the valve cover.
The only tricky part is replacing the round spark plug tube seals. Two small tabs retain the old seals, which have metal parts and can be removed by carefully pounding and prying. The new seals are made from some blue rubber like material. I lubricated them with a tiny bit of grease and they slide right into place. Some people put them in the freezer to shrink them.
I bought a tube of the fancy black Toyota FIPG "Seal Packing 103" at the dealer. A dab of this goes on six places on each head. The places are at the sharp turns and at the almost invisible joints where pieces holding shafts are inserted. The manuals have suggestive diagrams with arrows. The tube is enough for many automobiles.
I added two 5/16 washers to each of the valve cover bolts. This requires 32 washers, making it economical to just buy a box of 100 washers. Then I torque them to about 100 inch pounds, which is plenty snug. It is impossible to torque some of the bolts on the rear cover, so we snug those good and tight and hope for the best.
The Toyota service manual says to torque these to 8 N-m, which is about 70 in-lb.
Injector B has a yellow wire. Injector C has a blue and red wire. Both injectors have a black and red wire that goes to the same common. This is not ground however, but this wire can be swapped between B and C.
Injector B was repaired using a yellow and black wire pair.
Injector C was repaired using a blue and black wire pair.
Reattach the two connectors on the driver side of this harness, the one behind the engine that I broke the plastic tab on I secure with yellow vinyl tape.
With the harness in position, I can finish the repair of the chewed wires.
Reinstall the "wishbone" piece using 3 12mm bolts.
Reinstall the EGR tube. A big black brace has pivoted into the way and there is no telling if it goes under or over the EGR tube, so it has to come off. It is attached via a 12mm bolt.
Reconnect 3 connectors on the passenger side. Two easy ones up top, and one tricky one down behind. The one down behind looks like some kind of vacuum tube. These go on much easier than they come off.
Install new plug wires. I install the 3 rear plug connections now, as well as snapping in the rearmost brace, but leave lacing the rest for later. Some of the attachment points are not in place yet.
Attach a ground wire to the back of the intake manifold. Doing it now avoids nasty contortions to do it later after the manifold is in place.
On goes the intake manifold. Do not tighten the 4 bolts entirely to make it easier to thread in the bolts for the two brace tubes. Attach the passenger side brace tube via a 14mm bolt, then replace the 10mm nut that holds the power steering hose right next to it. Then attach the driver side brace. Once the braces are attached, tighten their bolts as well as the bolts holding the intake.
Attach the PCV hose and two ground wires to the stud nearby. Attach the brake booster hose on the driver side of the manifold.
Reattach the EGR assembly.
Reposition the wiring harness and reconnect it. Also this is the perfect time to fasten down the plug wires and connect them to the 3 front plugs/coils.
Reinstall upper radiator hose.
Reinstall throttle body. Attach bracket for connector under lower left nut. Two coolant hoses, One vacuum hose. Three connectors.
Attach the bracket for the cables.
Reinstall the black plastic stuff in reverse order that it was taken off.
Reattach the two cables.
Refill coolant.
Reconnect negative battery terminal.
Odometer 199359
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