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Thread: Spark Plug - How do these look ?

  1. #1

    Default Spark Plug - How do these look ?

    Removed one bank. Should I replace or are they ok for a few more miles ?

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    Wix

  2. #2
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    Unlike old textbook, with double platinum coated spark plug, it's hard to tell the remaining life expectancy through your photo.
    Just go by the mileage and any rust markings mentioned later.

    With NA and non-special compression ratio on our engine, the combination of OEM IG coil and specified spark plug have enough spark energy/dowel time even at max rpm so no benefit seen on spark dyno by increasing the energy.
    You are better off looking at the fuel pressure and INJ spray pattern.

    Most of the time, better checking the plugs at the rear bank for any dark brown rust markings at the mating edge of white insulator and the metal HEX body.
    Please do not confuse yourself with the light brown corona arching marking (just like in your photo, perfectly normal) against the dark brown rust marking (not good, sign of moisture/water entered the coil/plug hole).

    The replacement interval of NGK or Denso double coated platinum plug is about every 60K miles but depending on the moisture level, I replaced them even from around 30K miles on some of the NSX.

    Some of the Iridium ones are under different maintenance cycle so be careful.

    If using different spec spark plug, please make sure to use the one without the hole at the top terminal if your engine uses the 2pin style IG coil.
    It will destroy the centre terminal of IG coil inside the tube.
    3pin style IG coil uses different design so should be fine but better staying with no hole at the top terminal.

    Hard to see in your photo but looked like you are using heat range #7???
    Unless you have specific reason (modified engine, track only usage, etc), #6 is better suited for wide range of driving conditions under normal usage.
    Honda did use #7 on specific country/year model but went back to #6 soon after for the above reason.

    By the way, strictly speaking, the character 'S' after gap number '11' means special gasket in use.
    Therefore, PFR7G-11 and -11S are not the same.
    OEM is without the 'S' but considering the seating area design, not sure it makes the difference.
    I think the 'S' plugs were used on S2000, etc.


    Kaz
    Last edited by Kaz-kzukNA1; 12-03-2018 at 01:38 PM. Reason: extra info

  3. #3

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    Thanks for the reply Kaz. Yes, they are 7's, I found and read your article about the 6's & 7's, shortly after I posted this thread. A bit strange, as I've just trawled through all the service history paper work and the only time I can see they were replaced in the last few years was about 15K miles ago in August 2010 but the invoice states they were replaced with 6's. So they have been replaced by 7's since then but no record of who or when !

    I'll remove the rear bank of plugs tomorrow but ultimately I'll replace them with some new 6's.

    If they are fitted to S2000's, it'll be a bonus, as I'll have a replacement set for my S2000.
    Wix

  4. #4

    Default

    Yes, S2K takes 7Ss.

    So you'll have 1 1/2 changes' worth.

    Look a bit 'gappy' but a photo ain't a feeler gauge.
    Nick



    I find myself irresistibly attracted to cars that nobody else buys. The NSX is a classic of the genre because nobody buys it and yet its a fantastic car. Its got a wonderful compactness and simplicity and unpretentiousness to it. Honda rudely continues to make them whether we like it or not, even though there can be no commercial logic in doing so I thoroughly admire that. Rowan Atkinson

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