Quote:
Originally Posted by mblaucoupe135
Excuse my ignorance, but short of removing the plugs, is there any other way to determine if they need replaced?
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Well, misfires could be a sign the plugs need replacing.
But one wants to avoid running plugs to the point they result in misfires.
I'm not a fan of removing plugs to inspect them. If I suspect the plugs are due for replacement I just replace them.
Now once removed from the engine I will look at the old plugs to judge how each plug is performing. But so far -- thankfully -- I have not spotted an under performing plug.
Below is a pic of an old plug and new plug for my Boxster. Old plug had 60K miles, the miles at which Porsche called for the plugs to be replaced. Despite the old plug's condition -- and the other 5 looked the same -- the plugs were fine, that is with new plugs the engine did not react favorably (or unfavorably) to the new plugs.
You can see the center electrode has eroded. And the ground electrodes likewise have eroded. But new plugs did not make the engine run better, at least based on my seat dyno...