Lean Warning Settings
Something that has cropped up a few times recently that has confused some aviation customers using wideband O2 sensors hooked to the grey wire for AFR display into the programmer- When they are leaning, suddenly the AFR goes very rich and they get an O2 Error.
There are a couple settings in the programmer- Lean Warning and Lean Warning + Add Fuel. When the latter is turned on, the ECU automatically adds about 25% more fuel when it detects the AFR going leaner than 14 to 1 for more than a few seconds to protect the engine.
In aircraft applications where you'll be running near or lean of peak, these settings should probably be turned off to avoid both the warning and especially having the ECU intervene.
Hope this helps some folks who are wondering what is happening here.