How to get to the CX-9 spark plugs

Wow, that's the lowest service interval I've seen on a modern car in some time. What's even stranger is that it's 40K on both maintenance schedules. The only comment I'd make at this point (off my soap box) is that you should have a much easier time with a DIY than us folks with the V-6. Given you have the inline 4 access to the plugs should be a very simple matter once you remove the engine cover.
 
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2018 Mazda CX-9 Grand Touring / Deep Crystal Blue / Sand leather
40k for spark plugs on a turbocharged direct-injected motor sounds about right. I know the VW GTI and my car require new plugs around that mileage interval, for example.

Plug replacements are more important to do on a proactive basis for these kinds of motors because as the plugs wear over time, they may not ignite the air/fuel mixture as effectively compared to when they were new. That can result in dirtier combustion which can lead to more gunk/buildup on the valves, etc. Worn plugs are also not good for the ignition/coil packs and can cause those to wear more quickly.
 
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'11 Mazda CX-9 GT AWD
Found Youtube Video; helped a lot...

Found this video on Youtube and it was a huge help. Got stuck trying to figure out how to remove that damn intake manifold; couldn't decipher what screw(s) I was missing!

https://youtu.be/gPZrjQY0g5E

I finally did the plugs around 118k miles. It being my wife's daily driver I asked her if she felt any difference?

"No."

I wasn't expecting much as the engine idles fine and pulls strong. MPG have never been anything to brag about; I suspect they might go up a tenth or two if we were watching closely. Personally, versus a longitudinal engine, I found this to be a real pain. Did take the opportunity to clean the throttle body. For the mileage it didn't seem too dirty.

Tried to upload some pics but uploads kept failing.
 
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2007 Mazda CX-9 Touring
When you cleaned the throttle body did you move the butterfly that opens and closes or did you just spray cleaner at it.
 
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'11 Mazda CX-9 GT AWD
Sorry for very late reply; hopefully you'll see it.

I moved it and got both sides; as well as I could. That spring is pretty strong. I think I propped it open at one point.

When you cleaned the throttle body did you move the butterfly that opens and closes or did you just spray cleaner at it.
 
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MAZDA CX9 2009
Get a help. Ask ur spouse to press the fuel paddle, and put your ignition to
ON. No need to start. Meanwhile, spray the inlet as the butterfly valve is flipped
 
Just a quick heads up for anyone else performing this procedure. I just did this on my 2008 CX9.

The video at https://www.youtube.com/watch?v=gPZrjQY0g5E is great, but a couple of notes about it:

* The video and audio aren't always totally in sync (for instance he says "there's one vent line you're going to pop off" at 0:59 as he's pointing to a clamp that needs to be loosened - the vent line was already popped off a few seconds prior at 0:55)
* Reaching a few bolts would have been easier with the battery removed (especially the one for the bracket connected to the lowest bolt on the throttle body), but I left my battery in
* The air cleaner assembly has a wire harness that needs to be pulled out with a trim tool (in the video, it's already disconnected)
* I disconnected the throttle body completely to take it out and give it a good scrub down since it was filthy - a lot easier than doing it while still in the car
* My manifold was covered in loose grime - shop vac to the rescue, before taking it apart and removing it from the vehicle
* You don't need the more expensive MS 97118 kit. Instead you can get just the upper manifold gaskets in the 97120 kit. The throttle body gasket is Fel-Pro 61466
* The hoses behind the manifold were the biggest pain - a hose clamp tool would have been useful for sure - but even still the hoses were pretty glued on and I had to slowly work them off with a flat blade screwdriver
* The wire loom across the manifold required popping off 3 different connection points with the trim tool - presumably a model year difference
* My 2008 had the wire at the rear of the intake manifold just below the first hose that's disconnected (mentioned elsewhere in this thread). Manifold wasn't coming out and I thought it was snagged, but it was just due to the wire still being connected.

I also started getting white smoke from around the engine after doing the job, which I couldn't believe as I thought I did everything very carefully! It turned out that I hadn't seated the hose from the air box correctly (I think the air box side may have shifted a bit when I reseated the hose on the throttle body). In any event, that's the clamp right next to the MAF sensor - so it was presumably causing a bad mixture into the engine. I didn't get any codes and nothing was overheating - just a simple error easily fixed. I'm not sure that clamp even needed to be loosened in the first place to be able to disconnect from the throttle body, but I was following instructions.
 
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