2018 Mazda CX-9 Signature
I am pretty new at doing basic service jobs on my 2016 cx-9. I changed my spark plugs recently at 139k KM (I realize that this is way over the recommended 64k KM, but no dealer/garage had recommended it in the past and I only recently started reviewing my records to see where I was it). The old plugs still looked decent as far as I can tell by comparing to online photos (similar to those shown by Fawiek above). I had similar challenges with the re-insertion of coil packs 3 and 4 due to the tough angle. Took me quite a while to figure out that they weren't lining up straight on the top of the plug.
Ultimately, I was able to get the last pack in correctly, but the 8 mm bolt holding the coil pack in place made a awful plastic grinding noise going in and the pack in not tight like the other 3. It is fully in, but I can still move it a little. I don't think the car is misfiring, but I am not sure. When packs 3 and 4 were not lined up correctly, it was clearly misfiring. Now the engine sounds pretty normal to me, more or less like it did before. I just have this doubt because the pack wiggles a little.
Should I try to realign the bolt straight (maybe it went it at a poor angle... seems unlikely), or do I need to replace the coil pack (maybe I damaged the plastic on the pack?).
I welcome any advice... thanks!
So for the last bolt, you're unable to tighten the bolt any further, and the coil pack feels a bit more loose than the others? It's possible that you crossthreaded the bolt that snugs the coil pack. You could probably remove the bolt and try using a thread chaser to repair the threads, but then you'd risk getting metal particles in places you don't want them.
This is just a temporary solution, but I would find a plastic washer that would fit between the bolt and the coil pack, something just thick enough to shim the bolt up against the coil pack. Cut them on one side so that you can slide one or more under the bolt without having to remove the bolt.