454 Mercruiser MAG/EFI 385HP ...I have no clue what year this engine is.

These plugs were installed 3 years ago and they still look new, I don't see any carbon build up only a coating of engine oil.
Tyler Crockette retuned the engine back then and got rid of the rich condition Black transom.
I just did my first start for the season in my driveway and this could be fogging oil ? The engine idled for almost 10min.

Ayuh,.... The oil is probably the foggin' oil,....

Only thing I've ever seen that'll clean plugs like that is Water ingestion,....

looks like fogging oil.runn good?no stumbling?I'd pull a couple of plugs after a good run,,plugs are hard to read w/ the ethanol fuel but you should see some color.Thats why I love my afr meter.

spraying fogging oil thru an MPI intake / throttle body is not recommended plus you are really coating the intake runners along with any sensors that can be with in the bodies. .

search for soup mix up here to see how to lay up engines especially MPI marine engines .coating sensors and especially if applicable 02 sensors is not a good thing. I understand that you would not have 02 sensors but whomever does.

Thanks for the replies. The boat runs fine so I'm honestly thinking its fogging oil. I'm also considering that the plugs were not gapped correctly that's why the fogging oil did not burn off.
I gapped these plugs to 40 inch 3 years ago, I had to post a picture of where the gap is. Not sure if I gapped them correctly.

I read your plugs and I came up with NGK R .. hope this helps.

I was thinking the same thing. Lol

Temp of the plug needs to reach a certain temp for normal deposits to burn off. Not going to happen at idle, or in neutral at higher rpms for that matter.

Yeah big waiste of time to do a ten minute idle then pull the plugs and look at them. Hold it wide open for ten minutes turn the key off (without slowing down) then pull the plugs. That will give you a good wide open throttle read.

BTW, there`s no need to waste a bunch of fuel and a weekend trying to read plugs at different rpms.


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