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Mazda MX5 NC Spark Plug Change & AFM Clean

Getting a new car is always fun. Finding new things to do, things that need fixing and maintenance that needs… maintaining.

Thanks to my car being a Japanese import it has no service history. I know it needs an oil change (working on it, having some issues with the car being too low for my low profile jack atm), and I figured it probably hadn’t had the spark plugs changed in a while either.

First off, you need a willing victim.

Before I changed the spark plugs I decided to clean the Airflow Meter (AFM). This actually proved to be a very smart idea as although the air filter appears to be in good shape, the AFM was filthy.

This was probably one of the easiest AFMs i have ever worked on. Right there, in the front, easy to get at. Two standard Phillips screws secure it to the intake piping, not even torx or security screws like some brands use.

Unscrew the screws, disconnect the electrical connector, and it pulls straight out.

I hosed with down thoroughly with Electrical Contact Cleaner and let it dry. Once dry, reinstall and reconnect. Done. Easy.

With that out of the way I moved onto spark plugs.

Now, spark plugs can either be easy as, or a real pain in the arse. Thankfully Mazda doesn’t piss around, the plastic cover on the top just pulls off and then the coils and plugs are right there.

The coils are all held in with a single 8mm bolt each. I pulled each coil out one by one as I changed the spark plugs, so I didn’t mix them up. I didn’t even need to remove the electrical connector.

The plugs didn’t look too bad, or that great either for that matter. They look like they have been in there for yonks, and are showing bad discoloring on the ceramic. There wasn’t any buildup on the electrode, but the gap looks to have widened. They had a decent color too which is good. I used genuine LFJR-18-110 spark plugs.

Wind the plugs back in, by hand initially, and then hand tight.

Reinstall the coils, replace the cover and away you go.

In my case it’s like a new car. Idle is smoother, no more hesitation, and it pulls stronger through the rev range. Well worth it.

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