O2 sensor bias

[John Wickerham]

I'll add my bit to the discussion about O2 sensor biasing.  I
have a Chevy S10 Blazer with 4.3 Liter V6, TBI system.  It's
one of the '7747 ECU's.  I played around with biasing the O2
sensor high so that the ECU would think the engine was running
rich when in reality it was not.  The idea was to lean out the
mix under conditions when the ECU was looking at the O2 sensor.

I know for a fact that as a result of biasing the O2 sensor high
on this vehicle, that the ECU changed the EGR flow as well
as the pulse width of the injectors.  If you go too high with
the bias, the ECU triggers a fault and tells me that the duty
cycle on the EGR has exceeded 50%.

The point I'm making is that biasing the O2 sensor will do more
than shorten the pulse width of the injectors.  There may be
other side effects that negate what you're trying to do.

Later,
John