I was getting readings in the 9s and 10s before tuning and my boat was black, and would require new plugs after 20 hrs or so. At 8 I would think your engine would sound like 8 lawn mowers running. Also you should see some dancing in the numbers, if it is just locked on one exact number something is wrong

You mean mercury set their engines up towards the rich side?

Surprised it even ran, what a difference. I don't know about others, but there were way off on the 575, maybe they were trying to protect the xr drive? Lol

The O2 sensor is working since it reads 20.9 O2 ( atmospheric oxygen level ) and I did calibrate it outside the header.
My EGT's are low (1200*)
I can read the O2 and air/fuel levels off of the laptop bypassing the gauge.
I have dry headers.

Dry exhaust reduces soot vs wet exhaust, if you are truly running at 8 you should see black smoke every time you free rev that boat. If you are confident the o2 is correct what is your question?

8 afr is damn near a hydro-lock. It would be lazy, want to stall, load up, and sound like crap.

I'll ask again, is it locked on a number or is it moving around? Where is is at idle, cruise and wot? If you say 8 all the time something is not working

Just because it reads 20.9 in free air doesn't mean the sensor is good. 8's are pig rich, it will be a DOG. If it truly is in the 8's you are destroying the rings and cylinder finish.

do the plugs say its running in the 8's?they will be black.

Stab the throttle in neutral to about 3500 or so and watch the gauge as the revs drop. No way it is staying in the 8's as the engine decelerates. It sounds like the sensor is screwed.

Is this engine on gasoline or E85 ?

It is running on 93 octane. ( 10 to 1 ratio ) I ran it on 89 in the SCARAB. The pistons are 0 decked.
The sensor was working - Last night I was able to get a reading on the laptop that was plugged into the system. The gauge was not working.
It is working now.
I changed the ignition switch and some of the wiring under the dash. ( the wiring on this boat is atrocious ) I test fired the engine and I got a reading on the laptop and the gauge.
I will dial the engine in this weekend.
I have two of the HP 950's so I can TINKER with one while still having a non tinkered model on hand.