Alright here is a little how to on changing spark plugs in a 2007 CTS 2.8L. I believe its the same with a 3.6L but not sure. The way I did it was not to completely remove the intake manifold, I did not remove every clip and hose that is required to completely remove it, rather I removed what was necessary in order to get access to the plugs and COP's.
Disclaimer: I am not responsible for your actions or the well being of your vehicle. This is to document my experience with my own vehicle. Try this at your own risk. Now that thats out of the way on to the how to.
Total time: 1.25-1.5hrs
- Regular screw driver
- Various sockets, extensions & a ratchet
- Spark plug socket
1. Remove the engine cover, just give it a good pull and it will pop off.
2. Remove intake coupling that connects to throttle body
3. I forgot to take a pic of this but there is a stud near the throttle body that holds down the front of the engine cover that needs to be removed which holds a bracket, there also is a 13mm bolt that needs to be removed also, you will see it.
4. On the drivers side of engine bay there is a hose that needs to be removed. Located in this pic.
5. Remove this clip, hose & bolt shown in pic on drivers side.
6. Remove this hose
7. Now on to the passenger side, remove this bolt.
8. Remove the hose and bolt shown below.
9. Remove this bolt.
10. Now unbolt the 6 bolts holding down the manifold but dont remove them.
11. Ok once the manifold bolts are all unbolted you can move onto the plugs.
I started on the drivers side in the far back. You have to unbolt the bolt holding down the COP and then undo the harness connecting to the coil, then it can be pulled out and the plug removed and the new one installed.
12. I did the drivers side back 2 with no interference from the manifold, the one closest to the front is obstructed by the manifold but since you removed everything in steps 1-10 you can now lift up on the manifold that will get you enough room to get the coil and plug out.
13. Now that the drivers side is done, move on to passenger side rear plug, this one is also not obstructed by the manifold and can be removed easily. The front 2 on the passenger side need to have the manifold lifted up in order to gain access to the COP's. Below is a pic of me lifting up slightly on the manifold, I only had one hand so it isnt lifted up all that it can go.
14. Once all the plugs are in and COP's are bolted back down you can start putting everything back together and bolts tightened back down.
Hope this helps anyone that is not sure if they have the skills to tackle it, but it really isnt bad...all you have to do is unbolt stuff and move it out of the way.