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Hi,
As to removing the Lambda system:
The metering valves in a fuel distributor (small plate valves) control the fuel flow vs. pressure for each injector. They are spring loaded and have a lower chamber, connected to the control pressure. On a pre-Lambda system they have a fixed bleed orifice to the fuel return. On a Lambda system that bleed orifice is replaced by the frequency valve. When the FV is open, more pressure is bleeded from the lower chambers and more fuel is metered to the injectors. If the frequency valve is closed, the chamber pressure is high and the engine leans out. If you remove the FV and plug the line, the engine would run so lean that it would barely run at all. If you leave the line open the engine would run so rich it would also not run well.
The Lambda 'brain' opens and closes the FV about 50 times/second with varying duty cycle. That duty cycle controls therefore the bleed ratio of the lower chamber.
When the O2 sensor is disconnected, the Lambda controller defaults to about 50% duty cycle during idle and part throttle. When the WOT switch closes (or the 15 degC switch closes) the lambda brain runs a constant duty cycle of about 60% (varies depending on engine) and ignores the O2. When the O2 sensor is connected, the controller regulates the duty cycle such that the O2 sensor voltage is about 0.45V.
Regards,
Klaus
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