I've clocked mine at around four minutes from a morning start in warm weather.

But if this could be reduced to two minutes, and if the one-minute delay on
warm starts could be eliminated, I'd bet we could see MPG improvement of a
few miles per gallon.

My hunch, again, is that these delays were built into the ECU/O2 system to
please consumers by making the vans run smoother at a time when gas cost .75
per gallon or thereabouts.

I thought disconnecting the O2 sensor sent the ECU into open-loop mode. No?
Someone here said that giving the sensor wire 1.5 volts from a flashlight
battery would kick the ECU to closed--is that wrong?

Heated sensors are better, but I think there's still an engineering flaw
involved.