[mwebb]

Originally Posted by Daox

Increasing the EGR flow doesn't create a lean burn condition. It introduces more inert gas into the engine which dilutes the intake charge (effectively displaces oxygen). The O2 sensor will sense this and compensate by lowering the amount of fuel injected to maintain stoichiometric 14.7:1 fuel ratio. If you're getting misfires you're running too much EGR which will lower your engine's efficiency. You'll have to back it off a bit.

the load sensor either MAF or MAP sees / calculates less incoming air and this what reduces the injector pulse to maintain desired air fuel ratio .

EGR when active displaces the air fuel mixture
EGR when active dilutes the air fuel mixture
but
EGR does not and can not change the Air Fuel RATIO , the mixture DOES NOT become lean or rich
when EGR is active

and now
the next part
02 sensors as in Oxygen sensors
DO NOT SEE OR MEASURE OXYGEN content
02 sensors as in Oxygen sensors
DO NOT SEE OR MEASURE OXYGEN content
02 sensors as in Oxygen sensors
DO NOT SEE OR MEASURE OXYGEN content
02 sensors as in Oxygen sensors
DO NOT SEE OR MEASURE OXYGEN content

02 sensors / oxygen sensors see only
combustibles
and they report presence of combustibles to the ECM

Lambda sensor is a better word to describe 02 sensors
and if this word is used , there would be much less confusion in the ranks of the mortals pondering their use