GMC Acadia Forum banner

Not open for further replies.
1 - 1 of 1 Posts

Premium Member
3,371 Posts
Discussion Starter #1
I just changed the plugs, and found there was an overly-technical guide that did not address some of the problems I encountered, so I re-wired it for MORE POWER! Actually, I re-wrote the entire thing the day after I did the work, but I took some pics while doing the work that should be helpful.

Neither the PDF nor the MS Word doc for this would not link properly, so I'll go old school and post text & pictures. If you find any errors, please PM me and I'll update it.

As with most stickies, I'm locking this post to keep it clean.

Blue's Plain English Spark Plug Change for the GMC Acadia

There is a lengthy shop-manual type of listing for this job, but things like fuel injector sight guard made me think of bad things like excessive legislation. I figured having completed this job, I'd try to write it up with some photos to make it easier for the next person. I make no claim this is perfect, as I'm doing it from memory the day after, and my vehicle is a 2009 model. If I've missed anything, please let me know and I'll update this.

The good- It's not really that difficult.

The bad- you have to remove the intake manifold.

Tools needed-
3/8 ratchet with 3” and 6” extensions
3/8 torque wrench
10mm socket (coil pack & loom bolts)
13mm socket (intake manifold bolts)
5/8 spark plug socket (be sure it has a piece of rubber in it to hold the plug)
Flat blade screwdriver (intake boot)
Spark plug gap gauge/tool

Parts needed-
6 spark plugs
Lower intake manifold gasket. The more expensive “set” is not needed. I bought this at for about $17 (AC DELCO Part #12590958 ), they have a 5% off discount code that changes, so search online for it.

Supplies needed-
Rag/towel and general purpose cleaner to cover & clean intake area on engine
Antiseize (for plug threads)
(Optional) carb cleaner for throttle body

There is no need to jack or be under the vehicle. As an overview, you're going to pull the plastic cover from the engine, and then remove the intake manifold. This will give you access to the coil packs, which are on top of the spark plugs. The spark plugs are in deep wells.

First, remove the oil fill cap, then remove by pulling up the plastic engine cover. Replace the oil cap so no debris gets in there.

Next, remove the rubber boot/bellows from the air filter box to the throttle body. This has a clamp at each end with a regular slotted screw. Now would be a good time to check & replace your air filter!

Remove the electrical connectors (2) at the throttle body. One is in front and one in the rear., and they are different so don't worry about mixing them up. The rear one is a large plug and may take some experimenting as to which part to depress- I didn't take a picture of this and recall it was a little sticky to get loose.

There is a hose with a push button connector on it at the throttle body (the button on mine was green). Push the button and slide the hose off. There should be nothing else connected at the throttle body.

Remove the hose from the device by where the hood latch is (may be unique to 2009+ models). This is the brake booster hose, and also tees into the manifold at the front. Disconnect it by pulling it loose. You can leave it connected to the brake booster.

On the left side (as you are facing the engine, or the passenger side), there is a large plastic loom with wiring harness and a mesh covered loom with fuel lines. Each of these is clipped to the intake manifold and must be pulled loose. The older your vehicle the more likely these clips will break. Gently pull on them til the pop loose. I broke one on mine, and the vehicle was only 3 years old. There is a 10mm head bolt that clamps the loom to the manifold. Remove it, pull the loom away, and put the bolt back in place so you don't lose it.

My intake had sound insulation on it- kind of like felt on cardboard if I had to describe it. It will pull off if you go easy. I removed it and a couple pieces broke away.

Now you can easily see 5 of the 6 bolts that hold the manifold. The main 5 are very long, while the sixth is much shorter. All of the main ones are the same length, so you can't mix them up. Using the 13mm socket, loosen these. The 6th is hidden behind the throttle body. I took a picture here to help you find it. Here is the manifold off (bolt locations circled in red):

Here are two pics of the 6th bolt that are not in the PDF due to size (had to keep it under 1 MB, though a lot of good that did ::)):

With the intake removed, you can use your rag and some cleaner to clean the portion where the gasket will go.
I'd suggest you also clean the throttle body, as gunk gets in it over time. To do so, wet a rag with some carb cleaner, push the throttle blade open, and wipe away the grime inside as best you can on both sides of the body (you can only do one side while holding it open. You do not remove the throttle body from the intake to do this.

Here is what you'll have in the engine bay:

Go ahead and remove the old intake gasket (the brown piece with the rubber circles above) and carefully clean the mating surface. Take care not to push any debris into the openings. You can set the new gasket in place, and cover it with a towel to make sure no debris or parts fall into the engine.
The coil packs are held in place by one 10mm head bolt. Before you undo it, make sure the electrical connector is loose. It has a tab on it that slides. This is a BIG SECRET not mentioned in the shop manual excerpt I read.

With the connector open, you can easily pull it off the coil pack. With the bolt out, twist the coil pack until it pulls straight up. Use your long extension and spark plug socket to remove the plugs. Check the gap of the new plugs. Rock Auto showed the gap as .040, which seemed too small to me, but this is where I gapped them. Apply some antiseize to the new plugs and install them.

Finishing up
Replace the coil packs, tighten the bolts. Reinstall the connectors to the coil packs and close the tabs to lock them in. Remove the towel and set the intake manifold in place. Torque the bolts in a circular pattern starting in the middle to 17 foot pounds. Reinstall the sound insulation. Reinstall the loom bracket and tighten that bolt. Stick the retainer clips back in where you pulled them for the loom and fuel lines. Reinstall the brake booster hose. Reinstall the electrical connectors (2) at the throttle body. Reconnect the hose with the push button at the throttle body. Reinstall the air filter boot/bellows and tighten the clamps. Remove the oil fill cap and replace the plastic cover. Replace the oil fill cap.
1 - 1 of 1 Posts
Not open for further replies.