O2 sensor too eratic or is this common

[Tinkers Toy]

For the last 2 years now I have MS3 / MS3X and 4 channel driver providing semi sequential injection and wasted spark ignition to my V12 Mercedes, I have put about 2000 miles on the car. My LC-1 O2 sensor readings seem very erratic. The sensor is 3 - 4 feet from the heads. The duel exhaust dumps into a common muffler at the rear of the car. I'll describe the exhaust on each side. Each side has 2 ea. 3 into 1 exhaust manifolds on each side. Each manifold dumps into a 3 foot long tailpipe that goes into a 2 into 1 collector about 8 inches before the cat. The O2 sensor is mounted next to the factory sensor between the collector and the front of the cat. The cats have been emptied so the exhaust flows pretty freely now, they had been clogged causing problems. The car is running very well right now. It seems like my O2 sensor is working now but it just jumps around too much for my liking. The readings on this LC-1 jump from 11to 14 to 11 to 14. I'm using the average as the current reading along with checking plugs and in general sensing how the car responds. How stable should these readings be? My needle on the TS gauge sure jumps around a lot.

2015-09-01_20.28.32.msq

2015-09-01_20.34.54.msl

[kaeman]

jumping around like that says misfire, or exhaust leak, or dirty injectors. if it was just jumping around in the .tenths column then no problem but jumping 3 full points, says that something isn't burning correctly or fresh air might be getting into the exhaust some where or one or more cylinders are getting less airflow, possibly need to adjust valves.. my idle is relatively stable, the tenths column will bounce up and down 3 to 5 points. ie. 14.3 to 14.7 and back.

[turbo conversion]

After looking at your msq your timing verse rpm seems to be way to advanced, at least what I am used to seeing.
33 deg. at 1600 rpm seems way to aggressive to me and at 600 rpm I am seeing 20+ deg.
To much timing can cause miss fire that could contribute to your problem.
Not sure if this will help but it maybe worth looking in to.

David

[Tinkers Toy]

I'll try backing out the timing since that's quick and easy. There are no adjustments for the valves, duel overhead cams ride directly on lifters on the valve stem. 48 valves on this engine. The suggestion of air in the exhaust might be an issue worth checking out now that I know my sensor should not be jumping around like this. This engine has an air smog pump on it. I unplugged it but didn't block off the ports. I'll look at sealing them off. I can quite easily install a homemade copper gasket without a hole in it to block things off, it's inexpensive and worth a try. I do not hear any exhaust leaks that would indicate air getting in any where else. Thanks for the suggestions.