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System Operation and Programming Section
EM-6 Reset
Any time that the power is shut off or interrupted to the ECU, or if interference prevents the software from
executing properly, the EM-6 will automatically perform a reset. This takes about 0.5 seconds and the
engine will falter during that period. When this happens, the SDS EFI startup screen will appear in the
LCD window. Reset can also be caused by the switching of high current devices such as electric pumps,
motors or solenoids. These devices cause high voltage spikes that are difficult to filter. Filtering can
sometimes be successful if a rectifier diode is placed across the offending solenoid, motor etc. The
striped end (cathode) of the diode should connect to the (+) terminal and the other side of the diode to
the (-) terminal. Never attempt to fly the aircraft if your ECU is resetting on the ground! This
indicates there is a serious issue. Find it and fix it before flying!
Shutting off Power and Memory
Programmed values are stored in the ECU microprocessor in EEPROM memory, which holds the values
in memory when power is turned off, needing no battery power. As soon as you change a value with the
programmer, it is permanently changed and stored in EEPROM memory. Disconnecting the aircraft
battery will have no effect on the SDS system.
Disconnecting the LCD Programmer
Set the VALUES LOCK to the ON position before disconnecting the programmer. No data will be lost.
Data is stored in the ECU.
Injector Drivers
Injector drive transistors may be triggered in ones, pairs, threes or fours depending on application. Some
four and six cylinder aircraft ECUs optionally fire the injectors in ones to allow for individual cylinder fuel
trimming.
Air Temperature (AT)
The air temperature correction map is pre-programmed when delivered, and is not normally user
accessible. It provides an absolute density correction relating to cues from the air temperature sensor.
AT is displayed in GAUGE mode.
Mixture Knob (KNOB)
The mixture knob controls the overall mixture across all ranges. In effect, it adds or subtracts a
percentage to the injector pulse width. From the straight up or 12 o’clock position, the mixture can be
leaned roughly 50% by turning the knob fully counter clockwise or 50% richer by turning it fully clockwise.
The knob is very useful in determining a rich or lean condition and can be used in cruise flight for leaning
the mixture in LOP operations and we recommend it be mounted in all aviation installations. The knob
allows quick changes of mixture without re-programming in the event of some sensor or fuel
system malfunctions so should always be installed in aircraft. Be sure to complete all programming
with the knob in the 12 o’clock position so the ECU defaults to best power mixture with the knob at 0%
correction. Precise return of the knob to an exact position can be noted in gauge 2 mode under KNOB. A
+%, 0, or -% indicates rich, neutral or lean position.
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