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spark plugs, how do they look (img included)?

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  • #31
    Leaner the 2 and 3. It's all relative tho
    "It is needless to say that self-propelling vehicles, like other machines, will never do as much for one who does not understand them as for one who does."


    • #32
      Plug reading is not that easy to do. To really get meaningful readings, you have to abruptly shut the engine off when it is operating in the range you want to check. And there is a lot of overlap and variance of opinion as to what constitutes "lean"...."normal"....and "rich". I have never felt comfortable drawing too many conclusions from how plugs look, except I know oil on plugs is a bad thing. They should be dry.

      They should also look the same on the same engine. I find it curious that two of yours look different.

      I rely more on WBO2. If that reads right, and compression is good, and all the plugs look the same with no wet fuel or oil or signs of detonation, I don't worry too much about how the plugs look beyond that.

      I think to some degree plug reading is old school from the days of carbs and no modern diagnostic tools.



      • #33
        When I removed the plugs especially number 4 looked very odd to me. I did remove them to get a look in the cilinders because I had an issue with pressure building up in the coolant system. Plug 4 is a plug washed clean by coolant I now know. The head of my S14 cracked between the exhaust valves at #4. Signs of cracking at #1, #2 and #3 as well.

        Currently I'm thinking over how far I want to go with a rebuild + I'm considering getting some work done on the body as well.

        No M3 driving for at least a year :-(.