Spark plug reading?Are you a plug whisperer?

Discussion in 'Maintenance & Upkeep' started by Pikey, Feb 6, 2014.

  1. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    I changed out my plugs today and was curious if the markings on them mean anything. I have pulled oily plugs, really worn plugs, and so on from other vehicles, but am never good at identifying an issue unless it is major. I have one I saved from a 2002 explorer where the lead was worn down to a knife edge and the electrode was almost completely gone. On these, the lead looks pretty white from where it connects to the plug to the bend, the area of the lead after the bend looks black/brownish. could be normal. it is not very often that I get to pull "normal" plugs, most the time they are when someone brings me a car that has gone double recommended change mileage. thanks

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    Last edited: Feb 6, 2014
  2. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    Like you Mike, I have trouble reading "good" plugs, but they look like everything is working as it should.
     
  3. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts



    cool! Thanks for the response ray. I have a chart and it says white indicates that it is running lean or too hot. but, that shows the entire lead white, not just part of it and the tip black/dark brown. I ran a programmer on it for a while, but have since removed it to diagnose some odd noises I was getting. I am pretty sure that they are the original plugs, the dealer that I bought it from put new wires on it. But, the plugs i pulled are a number that they stopped making in 2009. I figure that the dealer would have installed the new part number. They don't look too bad for 160,000 miles. The gap was still good.
     

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