Oxygen Sensors
Normally there are two oxygen sensors present in the vehicle. The primary oxygen sensor is used by the ECU to control closed loop operation. The secondary oxygen sensor is used to check the performance of the catalytic converter, and also alters the closed loop target lambda in order to provide the optimum mixture for the catalytic converter.
Primary oxygen sensor
For tuning it is recommended to keep the primary oxygen sensor enabled, in order to prevent any tuning differences once switching back to open loop.
Secondary oxygen sensor
The secondary oxygen sensor should be enabled unless running on a race vehicle with no catalytic converter.
MAP WOT determination
This table contains the manifold pressure used to determine WOT (wide open throttle = high load). At WOT the ECU will switch to open loop and use the WOT lambda adjustment tables.
Also see Wideband lambda interface