EGO sensors work at stoich because

[Phil Lamovie]

Hi All,

EGO sensors work at stoich because they were designed to.

Better question is who wants it in the first place ?

Answer... the catalytic converter needs the mixtures to be very close
to lambda if it has any chance to do it's job. Slightly rich say 0.95
to reduce nox by reduction and slightly lean say 1.05 lambda  to
oxidize hc's by way of  combustion.

Worse than that it needs to oscillate between the two quite often. At
least
3-5 times a second. It's all quite tedious and has not got a DAMN
THING to do with how an engine wants to run.

The mere words closed loop and O2 sensor (which it patently isn't)
give me the willys. Never confuse pollution control with correct
engine management. Never use a single wire O2 sensor for doing
anything other than filling the whole that it came in.

If that's a sensor then a ruler would be a piece of wood with 1 foot
written on it in words with no other markings. This "sensor"  would
allow you to judge if an object was more or less than a foot long but
not anything else.

Same with a simple O2 sensor. It only sees richer or leaner than
lambda and any $10 voltmeter attached to it would still render it an
on/off switch.

Your in didactitude..

Phil