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.
LAF voltage to lambda
This table contains the conversion from the stock wideband oxygen sensor to lambda (air/fuel).
Also see Wideband lambda interface
Closed Loop Target Lambda
This controls the target lambda (air/fuel ratio) when the vehicle is running in closed loop. A combination of tables is used the set the target lambda, based on temperature and load.
The target lambda used is the richer (lower lambda or air/fuel ratio) of the 'Closed loop target lambda', 'Closed loop target lambda limit' and one of the 'Closed loop target lambda load' tables. The transition from low to high load is at approx 50 kPa.
Warning: Running leaner than stoichiometric (lambda 1, approx 14.6:1) will increase exhaust gas temperatures and also increase emissions. For this reason it is not recommend to change these parameters on road vehicles.
Short Term Fuel Trim Min/Max
This controls the minimum and maximum percentage of short term fuel trim the ECU compensates for while in closed loop.
