The reason for 4Bar was only because that's what was available in a component configuration that would fit the circuit board in a dual installation. I checked the readout for accuracy against a 2.5Bar sensor and found it was plenty fast, very stable and gave the same reading as the 2.5Bar.

Even if the reading wasn't quite as accurate - with dialed in VE tables the wideband readout should allow the EGO correction to adjust the fuel to hit the AFR table value.... as long as I set the parameters to give enough controller authority to the EGO circuit. The idea with VE table tuning is to start with about 80% authority, let it make table corrections centering within the range and gradually work the authority down to around 10% once everything is dialed in.

All of the sensor readings are relative anyway - and repeatability around a given vertex is more important than the actual number - because once you get on the dyno and adjust the AFR table numbers for max power to give the engine what it wants, it is what it is - no matter what number value is assigned. Also, the wideband o2 sensor and EGO circuit has the final say to bring the fuel trim back to the AFR target. Since the o2 reading is independant of any input data except the exhaust gas, it is used by the EGO circuit to modify the injector pulse width to bring the mixture back to the AFR target that was established on the dyno as ideal..... no matter what the VE table says.

I think there's a trade-off between a tight controller for accuracy and a loose controller for safety. It seems to me that if you dial it in tight and have a fueling or sensor issue, the controller may not be able to react to the needed extent to save the engine.

I don't know what the upper limit of the VE table will be, but I would guess it's not going to be more than 120%. It really depends a lot on the VE of the base engine. What would you say - 80%? If so, and that represents 143HP and I think I now have ~210HP designed in - then that represents a 50% increase in efficiency - or about 120%. The actual math may not be that linear, but I would be surprised to see a peak VE much over 100%.

There's a whole lot to learn with MS and I'm still a rookie. The more I learn, the more questions I have. Maybe one day it'll come easy, but it's not easy getting to easy.

Frank