Sounds like a good idea. I'll take the boat out this week and get a true reading from the plugs.
Tyler Crockett reprogramed the mapping 3 years ago I think it's time for another visit. He had me install O2 bungs on the exhaust to clear up mercrusers rich condition.

Reading a plug will tell you how much timing the motor wants and also the heat range it wants. Widebands are great tool but only help with a small piece of the puzzle.

Have to ask shutting down engine at full throttle - you never sucked water back - water reversion of any form or shape taking place ?

engine diesel and or huge wake running back thru the exhaust ? I understand you can turn the boat at shut down. If you have thru prop exhaust I do not recommend doing that. I realize most have thru hull exhaust but not everyone and silent choice apps. included.

95 mph shutdowns on my Donzi it it would sit down off plane better than if under power. This was with bravo style dry exhaust.

I had to do that once when my throttle linkage jammed. I was running along at WFO, and when I pulled back on the stick it just kept happily winding out. I had to pull the lanyard and steer it into a turn. Even then, ad BUP described, the engine dieseled, burped and farted. (the fart might have been me) Not the preferred way to shut down! It won't hurt anything to briefly pull it back to idle and slow down safely before you cut the key. Just don't idle all the way back to the dock.

That being said, as mentioned, with today's fuels it is almost impossible to get a good plug reading. And you really have to know what you are looking for. A buddy of mine farted around with his for half a summer and got nowhere.

You should change your name to plug whisperer if you can tell all that with 15% ethanol.

Ground strap will still show heat and little tiny aluminum sphere specks down in plug will still show detonation - no matter what fuel is used.

A wideband cannotshow that to you.

Speakin of wideband not showingeverything.

anyone ever think about the fresh air/fuel being pushed out into the exhaust and how this effects your wideband reading ?

Schit,anyone ever think about that with 100%+ VE on the dyno ? 110% VE (just to pick a number) does not mean trapped, 10% or more of that could have been pushed right thru unused.

Honestly I didn't know it was an issue reading plugs with any type of fuel until I got on OSO.

Everyone has a different way of doing things I guess .
Why run around for hours at different rpms trying to look for some sign of color on 2 motors burning $5/minute when I can just look at a AFR meter and know the exact fuel ratio down to the tenth of a point?
I still pull plugs after every weekend but it`s not for air fuel readings.