Vibration at idle, gone with spark plug change

Fair enough, I'll say that if you don't have a problem, don't change them.
Replacing spark plugs at the recommend 75,000 miles is for preventive maintenance. You can also not to change the factory engine coolant at recommended 120,000 miles or 10 years without immediate issues, but eventually it would cause problems. Another example is the ATF change. Although you believe its not necessary, but those used ATF analysis reports from BlackStone show the ATF does wear out over time. ;)
 
Replacing spark plugs at the recommend 75,000 miles is for preventive maintenance. You can also not to change the factory engine coolant at recommended 120,000 miles or 10 years without immediate issues, but eventually it would cause problems. Another example is the ATF change. Although you believe it*s not necessary, but those used ATF analysis reports from BlackStone show the ATF does wear out over time. ;)

Agreed. Though in the future I'll replace the spark plugs with the cheaper NGK variety. The OEM's I purchased had the same model number as the NGK's printed right on it, but it was like double the price.

Could be placebo affect, I don't know, but I do feel like mine runs better since replacing them. Feels a bit more peppy to me and wasn't lagging ass in some situations anymore. I agree everybody is different. Different driving styles, etc.
 
Quick update after driving about 4K miles with the Denso Iridium replacement spark plugs. No perceived performance difference vs the stock plugs when new. They were half the price of the NGK plugs so I can recommend them if you need them (thanks yrwei for finding some CX-5s came stock with these).

I was initially worried that I was getting lower mpg with the new Denso plugs, but Im pretty sure I replaced the spark plugs the same week winter gas came to the FL area. I get about 31-32 mpg on the highway in summer, and I briefly forgot I get 29-31 in the winter. Im getting 32 mpg on the highway again as of a few weeks ago so I think we are back on a summer blend of gasoline.

I know some dont believe that winter vs summer gas can have a noticeable mpg effect and it might be due to other factors. However, central Florida temperatures are much less extreme and seem to be a good test environment and the CX5 seems to be somewhat sensitive to it in my experience.
 
I was going to do my 2016 GT FWD CX-5 spark plugs soon too, good to know it'll hopefully eliminate some vibration in mine as well.

I was going to get the NGK Iridium IX spark plugs to do this. Sounds like quite a few have had success with those ones.

Would like to replace the spark plug wires as well but can't seem to find anything online about them or parts to purchase in order do so. Am I missing something? Or can someone point me in the right direction to complete this work as well?
 
There are no spark plug wires. Our engine uses the Coil On Plug (COP) system. No need to replace the coils unless you are getting a misfire code. P.S. - note that you'll need a non-standard spark plug socket, it's listed somewhere in this forum.
 
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There are no spark plug wires. Our engine uses the Coil On Plug (COP) system. No need to replace the coils unless you are getting a misfire code. P.S. - note that you'll need a non-standard spark plug socket, it's listed somewhere in this forum.
Its 14mm spark plug socket.
 
Sometimes when my 2014 2.5L CX5 engine seems to idle not as smooth as Usual that a good highway run through the gears to the red line really helps. Don't be timid, just put the peddle to the floor and hang on. Ed
 
^Eds suggestion does help.

For grins and giggles I cleaned my intake valves using Felixs method (B12 chem tool after removing intake manifold). My valves at just under 70k miles looked just like his (about 20k miles?). I think thats just how theyll always look. The carbon was soft and cleaned off easily and definitely wasnt rock hard. About 40 miles a day of my driving at the time was at 55-75 mpg so Im sure that helped keep them in good shape

Cleaned the throttle body and MAF sensor while I was at it. The engine purrs like new at idle. No appreciable change in mpg or power delivery though. I continue to get great MPG consistent with the sticker when I bought it new. If you do mostly highway driving skip the valve cleaning. A lot of city driving? Yeah, it may be worth doing. Im sure itll go back to have a barely discernible vibration in another 10k miles when the intake valves get some crud back on them.
 
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