This is about vehicle repair, which has inherent risks of injury, death and property damage. You can also cause damage to some very expensive and hard to get at parts if you mess this up. When in doubt, consult the services of a competent mechanic. While the price may seem high, it could prevent you from breaking expensive parts. This is not an easy repair, as the rear bank is hard to reach. Do this and any other repairs at your own risk.
The vehicle we have is my 2006 Pontiac Torrent, which for all practical purposes has run like a Swiss watch. For the past few weeks, this vehicle has started hard, but it has always started. I knew this was going to be an issue and still put changing the plugs off. To my knowledge, they had never been changed but as long as it halfway ran so be it.
Today, it took five tries to get this pig to start. Each time, the engine would sputter and die. It also ran rougher than a cob. I went over to the auto parts store, namely the Auto Value in Grand Ledge and bought six spark plugs to the tune of $45. These were nearly $7.00 apiece and the reasoning that they were the AC Delco Iridium plugs that came with the vehicle, as said the part counter person didn't make it easier to swallow. Oh well, time to get busy.
Changing spark plugs on a traverse mounted V-6 is never a fun thing to do. On my Rendezvous, this was next to impossible without rotating the engine and removing the spark coils and ignition module. Even then it would be a pain in the rumpus to pull the boots and change the plugs on the rear bank. I never did it, and in fact traded the car. This wasn't because of changing the plugs, but the general condition including the tires, suspension and frame, but I'm digressing.
The Pontiac Torrent/Chevrolet Equinox isn't going to be a cakewalk either, but will be much easier with fewer tools and less headache. You need a 3/8 drive socket wrench, a 5/8 spark plug socket, a five and a six inch, 3/8 drive extensions, a 10 millimeter socket, a small blade screwdriver, as well as six AC Delco plugs that fit the vehicle. This is not something to skimp on as you will be changing these plugs again in short order if you buy cheap plugs. Buy the Iridium ones with the 100,000 miles warranty. You might also want a set of spark plug boot pliers, and will NEED some anti seize compound and some dielectric grease. The former will keep the new spark plugs from seizing inside the cylinder head, and the latter will allow you to remove the wire boots without pulling a muscle and save you lots of cursing and damning. A piece of windshield washer tubing to slip over the rear plugs could help too. You can use these to screw the plugs in without cross threading them.
Speaking of damning, you want to remove the engine undercover. Unclip the electrical connector from the EGR valve with the screwdriver; the plastic tab is on the inside of the connector. Do not yank on the wiring as this should come off easily. Then you can remove the cover by removing the oil cap extension and lifting the cover off the intake manifold. You can leave the cover off, but you need to install the oil cap and extension. All this stupid cover cover does is make the engine look slightly prettier, dampen engine noise, and maybe protect the canister purge solenoid. As for the solenoid, you would also remove this from the engine. Press the white retainer and pull gently to remove the line, unclip the connector, and use a 10 millimeter wrench or socket to unscrew the retaining bolt. The solenoid should pull right out. Be careful as this is a plastic part that will break and hence the reason to remove it.
This is a $35 part that will set the malfunction indicator light in a heartbeat and while you can use glue to fix this, my advice is to move the part to a safe location. Now, for the hard part. If the ignition wires are in good shape, keep them. If they're numbered, great and if not, take the time to label these with masking tape and a marker where they meet the coils on the rear of the engine. If you mix up these wires, your vehicle will do its impression of a bucking bronco. Go ahead and remove these wires from the coils. I would start with the rear plugs as it would be useless to do the front and give up on the back. You need to work the wires loose at the boot first.
Then work the plugs loose, one by one. Add some anti-seize compound to the threads before reinstalling the plugs. This is where the tubing might help. This will grip the plugs enough to allow you to start the threads. If they're cross threaded, the tubing will slip on the plug, preventing damage to the cylinder head. I used a regular socket and extension with my fingers to get these threaded in without a problem, but do what works for you. Reinstall the wires to the coils, then change out the front bank plugs. These will be a cakewalk. Make sure you add dielectric grease to the inside of the wire boots. Once you get the wires hooked up, reinstall the canister purge solenoid and the...cover if you want. Start the car and make sure it runs right with no lights. Then you're good for another 100,000 miles or when Jesus comes back, whichever is first. Maranatha!