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This allows you to program a target air/ fuel ratio (AFR) at each RPM break point
Closed Loop Enable/ Disable Switch (Optional)
This external switch allows you to quickly turn the closed loop function on or off without using the keypad.
Grounding the switch enables. See electrical section for hookup. If you have an additional external
closed loop enable/disable switch and prefer to manually control when closed loop is active, select the
window below:
Having the switch is recommended so Closed Loop can be turned off quickly.
When closed loop is selected off, no AFR targets will display in the RPM Fuel value slots. With closed
loop selected on, you’ll see target AFRs appear in the RPM Fuel windows. With the > flashing cursor
pointing at the AFR target number, you may use the + or – buttons to increase or decrease that AFR
number as below:
The + button changes the AFR target in increments of 0.2.
Press the > button twice to move to the next RPM programming range.
Best power is obtained around 12.5 AFR, best cooling around 10-11 AFR, best economy around 16
AFR.
.
Octane Select Switch (Optional) On systems controlling ignition
This external switch allows you to offset ignition timing a programmed amount of degrees when using
lower octane fuel such as Mogas. Grounding the switch enables ignition retard.
The first screen allows to to set the minimum RPM activation point for this feature. The second screen
allows you to set the degrees of ignition retard when activated.
Fuel Cutoff, Rev and MAP Limiting
RPM and MAP limiting in SDS are very harsh so it is not recommended that you constantly hit the rev
and MAP limits with SDS. These limits are intended for protection only, primarily for propeller governor or
blade loss conditions. Set them slightly higher than your maximum limits so you don’t run into them in
normal operation.
Fuel Cut /RPM
This will limit the RPM’s of the engine by cutting off fuel if the engine rev to the set RPM. With a setting of
2900 the engine will rev to 2850 RPM then at 2851 RPM fuel will be cutoff., depending on rpm steps in
your programmer. Adjustments are in 100 or 250 RPM increments. RPM. Lycoming Conti 2900 usually.
Rotax, much higher around 6000.
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