The Lambda Overlay is used to show datalogged lambda (air/fuel) values on the fuel tables.
Target Lambda
The target lambda is used when calculating the fuel change from the lambda overlay.
Note that the target lambda is not an ECU table, and changing these settings does not change the ECU fuel behaviour.
Overlay Lambda Input
This allows an external wideband input to be used for lambda overlay, or either the corrected or uncorrected stock oxygen sensor values to be used for the lambda overlay. It is recommended to use the uncorrected stock sensor for closed loop, and either the corrected stock sensor or external wideband for open loop.
Options
In closed loop apply fuel trims - will adjust the measured lambda in closed loop by any fuel trim (both short and long term) that the ECU is applying. This gives a more accurate fuel adjustment value in closed loop.
Calculate for each cam angle - will calculate and show the lambda overlay for each cam angle fuel table. Has no effect for vehicles without VTC.
Transition delay - specifies the time delay between the throttle reaching the minimum value and lambda values being shown on the overlay. This is because it takes a small time delay for the oxygen sensor to start reading the lambda again after overrun. This delay is also used by the autotune function.
Maximum interpolation - specifies the maximum distance between table cells where a lambda or sensor overlay value will be used. eg if cells are at 3000 and 4000 rpm and the engine speed is 3850 rpm, then the datalogged lambda value will be applied to both the 3000 and 4000 rpm cells, using a weighting based on the distance from each cell. For this example the 3000 rpm cell lambda value has less weight than the 4000 rpm cell lambda value. If the maximum interpolation is set to 80%, then the cells will only be updated if the engine speed is without 80% of the distance between the cells. For the example, the 3000 rpm cell will not be updated because 3850 rpm is more than 80% of the distance between 3000 and 4000 rpm, while the 4000 rpm cell will. This has the effect of filtering out overlay values which are too far from the actual engine speed and load. In practice this interpolation is weighted over two dimensions, so the maximum interpolation value applies to each dimension. This interpolation value is also used by the autotune function, except in the autotune function this value is used to calculate what percentage of the change to actually apply. For example, if a fuel cell value stands to be increased by 10% and the maximum interpolation value is 80%, then the fuel cell value will be increased by 8%.
Minimum and maximum throttle - the minimum and maximum throttle boundary for lambda overlay values to be shown. Typically the lambda will go very lean during once the injectors shut off due to overrun, so setting a minimum throttle opening will prevent these lean lambda values from showing on the overlay. This boundary is also used by the autotune function.
Minimum and maximum gear - the minimum and maximum gear boundary for lambda overlay values to be shown. This boundary is also used by the autotune function.
Minimum and maximum cam angle - the minimum and maximum cam angle boundary for lambda overlay values to be shown. This boundary is also used by the autotune function.
Minimum and maximum MAP - the minimum and maximum MAP boundary for lambda overlay values to be shown. This boundary is also used by the autotune function.
Minimum number of samples - the minimum number of samples of a cell for lambda overlay values to be shown.