Spark plugs after 10k miles - Miata Forumz - Mazda Miata Chat Forums
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NB (1998-2005) NB Miata discussion within. In 1998, Mazda released the second-generation MX-5, production code NB, for the 1999 model year.

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Old 10-10-2011, 06:53 PM   #1
BAMFr
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Default Spark plugs after 10k miles

so I pulled my spark plugs to do a compression test today, I got good numbers:

180-185 on all cylinder (cylinder 3 was 175-180, nothing serious). but my plugs look ok/odd at the same time. I am not sure if there is anything wrong, so if anyone here looks a these things frequently please tell me if I am wrong on my conclusion here:

The coloring implies I am running ok, but perhaps a little lean or too hot on cylinder two as the white is too far back on the ground strap. I also have that peeling on the porcelain on cylinder two. I had oil/fluid on cylinder 1,3,4 threads. Cylinder 1 I was expecting as I spilled some oil around it earlier in the weekend, and didn't take the plug out to clean it.

What the ---- is up with my cylinder 2 plug? I am baffled why that one would be overheating and not cylinder 4.

have a looksy guys:
Cylinder 1:



Cylinder 2:



Cylinder 3:



Cylinder 4:




Group pic.:
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Spark plugs after 10k miles-imag0395.jpg   Spark plugs after 10k miles-imag0396.jpg   Spark plugs after 10k miles-imag0397.jpg   Spark plugs after 10k miles-imag0399.jpg  
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Old 10-11-2011, 11:18 PM   #2
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I will update this with more info which I can concluded from discussion on other forums. The white isn't actually so white, this plugs are probably not doing so bad. spark plugs #2 has deposits and not cracking or damage to the porcelain. So I am not detonating like I had initially thought, but just to be safe I will be running 92 for the next couple thousand miles.

I am going to post a few more images of #2 which helped me in coming to a conclusion...
Attached Thumbnails
Spark plugs after 10k miles-imag0413.jpg   Spark plugs after 10k miles-imag0402.jpg   Spark plugs after 10k miles-imag0412.jpg   Spark plugs after 10k miles-imag0401.jpg  

Last edited by Track; 10-12-2011 at 11:59 AM.
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Old 10-11-2011, 11:27 PM   #3
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its deposits from my disappearing oil!! so some progress has been made then. The car has been eating oil at a relatively quick pace. I have posted a ton of links around, but this one is particularly good:
http://www.spark-plugs.co.uk/pages/t.../diagnosis.htm

and this one too:
http://dodgeram.info/Engine-Gas/Spar...plghnbook.html

These two confirm my suspicion that my leak has been from my valve seals/seats because the deposit on #2 is only on one side rather than all around.
With this said, the combination of leakdown test, compression test, and the deposit I should be able to determie if its a valve seat or valve seal (if its a seal, it won't show up on the compression or leakdown test since they are not part of the cylinder).
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Old 10-12-2011, 11:30 AM   #4
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Looks like light oiling deposits to me.
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