"If the duty cycle is 50 percent it means the mechanical mixture is spot on stoichiometric,...

Duke[/quote]

I think Stoichiometric gives a Lambda output voltage of about 0.45 to 0.48 volts (check this) on the black wire of a 4 wire O2 sensor.

I thought a 50% duty cycle meant the injectors are open 50% of the time....I am learning from this Web Site but have I missed something in this thread? At idle I would expect a duty cycle around 5 to 10% and WOT 85%.

In fact may I ask if anyone knows the idle duty cycle for a standard M119 engine?

Jim.