lambda is read only after engine is warmed up and system goes to closed loop.

The .050 volts might just be the base voltage when duty cycle is zero, I don't know. Do you have a good ol' fashioned dwell meter. Dwell is nothing more than duty cycle measured in rotation degrees. It would be a good way to cross check your other instruments whatever they are. Center of the dwell meter scale is 50% duty cycle.

Hope this helps,