Hi,

Here's a trick for a quick free-air calibration of the LC-1 and LM-1 that will work with modern ECUs that have a "flood clear" function. With those the injectors won't fire when the gas pedal is pressed fully down while cranking (to clear flooding). On most cars 10-20 engine rotations should be enough to clear out any leftover exhaust gas, depending on sensor location and exhaust system volume.
Switch the engine back off before you get off the throttle though, so it wont inadvertantly start.

I tried it on a 2000 Honda Civic. 5-6 Seconds cranking at WOT was enough for the LC-1 to show the same O2 content as in free air (freshly calibrated with the sensor out before I tried it). Results may vary with your setup, but you can easily try it for yourself. Post the results, as others might want to use that too.

Regards,
Klaus