SuperXtune Tune Editor

Air Per Stroke

This Tune Editor screenshot shows the Air Per Stroke (APS) Maps for both cylinders. The color mode shown displays each cell with a background color based on its value. These maps represent the air per stroke that enters the engine for a given RPM and throttle position (actually total intake area). The ECU uses these values to estimate engine loading for the given operating point. This Engine load is used as the x-axis to index into many other maps. You must resist the temptation to increase fuel by increasing these values. Since increasing engine load will "skew" the ignition timing map as well as any other map which uses engine load as its x-axis.

Engine Load is calculated by dividing the current operating point's APS by max APS. The max APS for the 8320 is 700.0 mg of air and can be accessed on the APS Misc page of the Tune editor. Also, if it is determined that the APS does need to be increased and in particular if the largest value(s) in the table need to be increased, you must also increase the Max APS parameter and redistribute the APS Engine Load Axis values in order to preserve the correct range of calculated engine load (current APS/Max APS). This is exactly what is not done correctly in the 9110 and the BRW tunes.

The next screenshot shows the APS maps with the Tune Editor in compare/percentage mode, comparing the BRW to the 8320. You can edit while in compare mode and/or percent mode and/or color mode.

Air/Fuel Ratio

This screenshot shows the A/F Ratio page for the 8320 tune. There are two maps used for determining the A/F ratio. A/F #2 map can be considered the full load A/F ratio map. It is used when the throttle position is above the threshold specified in the Full Load Map (at a given RPM). Below the throttle position threshold the A/F #1 map is used. For A/F #1 notice how the x-axis is Engine Load.

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This correct way to add fuel is by lowering the A/F ratio in either A/F #1 and/or A/F #2, allowing changes to fueling independent of ignition timing.

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This is the A/F page of the 8303 tune. Notice how the 950 RPM column is all 14.7 compared to the 8320 (above) which is 14.0 for the 950 RPM column. This forces the 8320 open loop at idle. The ECU enters closed loop operation any time the current operating point's A/F ratio is equal to the Stoichiometric constant regardless of the condition of the O2 sensor or if an O2 sensor is even connected.

On this page you can also adjust the A/F during warm up. The values are subtracted form the current operating point's value (A/F #1 or A/F #2).

Ignition

This screenshot shows the Ignition timing and the ignition timing limit for the 8320 tune. Again notice how engine load is the x-axis. Incorrectly inflated APS values will skew these maps resulting in incorrect ignition timing.

This screenshot shows the BRW Ignition map compared to the 8320. Note: this is displayed in absolute comparison mode, not percentage mode. Quite a bit of ignition added at full load.

More Tune Editor Screenshots and Details Coming Soon!