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Discussion Starter · #1 · (Edited)
This set of plugs has approximately 7 years and 40k miles of use on them. The car itself has 145k total miles, a Dinan tune and an intermittent misfire. I'm replacing the CPS sensors, O2 sensors, spark plugs, coils, doing vanos maintenance \ cleaning, and various other maintenance items.

The left plug is the back of the engine (by the firewall) and the right plug is the front of the engine (by the headlights).

Do the plugs indicate anything scary? Not sure why the driver's side plugs are so much more corroded on the outside compared to the passenger side.
 

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#1 looks a little oil fouled but the pictures are not good. The nut part look bizarre, never seen that before but it likely has no effect.
You have to look at plugs closely to determine anything, magnifying glass close. You also need to look at the bottom of the insulator. I give you a link so you can look at them yourself and decide.
At the bottom of this post on coils is a good basic on what you want to look for.
 

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Discussion Starter · #3 ·
#1 looks a little oil fouled but the pictures are not good. The nut part look bizarre, never seen that before but it likely has no effect.
You have to look at plugs closely to determine anything, magnifying glass close. You also need to look at the bottom of the insulator. I give you a link so you can look at them yourself and decide.
At the bottom of this post on coils is a good basic on what you want to look for.

Thanks 👍
 

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Honestly, from pictures they look very typical for 40k miles plugs that were not in the engine that had serious problems. If anything, you might be running a bit lean, but that might be the case of me not seeing things right on the pictures.
 

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Not sure why the driver's side plugs are so much more corroded on the outside compared to the passenger side.
I've had plugs(the outside part) looking like that in less than a year on 540s(e34/e39) when running without the covers above coils(on e39 water came from heated spray nozzle that was broken on the hood(hood was missing insulation too)).

You have likely had water in there on driver's side somehow.

edit: too much water in there, and you get occasionally misfires too.
 
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