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Number of Cyls
Number of cylinders of the engine. 4,6 or 8. Setting is locked during engine running to
prevent an accidental change.
Map Type
74” HG AB will be the aircraft setting, good for normally aspirated and
turbo/superchaged engines up to 74” Mercury Absolute. For automotive applications,
select 22PSI for PSI boost & Inches hg vacuum. There are a variety of other settings
for sensors which can be externally connected for higher levels of manifold pressure.
Gauge Diag1
This screen is used mainly for factory testing, but could also be used for
troubleshooting purposes. This screen allows viewing of critical voltage levels feeding
the coil packs in the system. Low voltage readings can indicate resistance in wiring or
poor connections, breakers and fuses. Losing voltage to the coilpack can weaken
spark so this screen could be useful in narrowing down a problem in the electrical system.
CPi-2’s with serial number 30 and lower, CP should read about 10 to 12 volts higher than the power source voltage,
so 24 to 26 volts is normal here. CPi-2’s with serial numbers 30 and higher, CP should read about 4.5 to 5.5 volts
higher than the voltage power source. This higher voltage is needed for the switching circuitry in the CPi2 unit.
CS is Coil Supply voltage from Mainbus power.
PC is voltage going out to the coil pack positive supply wire of the Primary Coilpack.
BC is the coil pack positive supply wire of the Backup Coilpack.
Only single board units will display both PC and BC readings.
Dual board systems will only show either PC or BC but not both, on the bottom line of the display. Press PROG key
and look for this screen in the backup boards settings to view BC voltage.
If CS is reading zero, then there is no power source to the CPi2 units coil power section and there will be no spark.
Check wiring to the CPi2, check the CPI2 fuses, and also check airframe fuses and breakers. Without coil power
supplied the switching circuits in the CPi2 will switch over to backup battery to power the coilpack(s).
Rev Limiter
No photo. Cuts off spark at the setting shown. Increments are in 100rpm steps.
For Dual board systems, be sure to switch over to the B unit by pressing the PROG key, and set its setting the same
as the A unit. Settings need to match if not the engine will rev to the highest setting of the two.
On Batt Coil Time
This can extend backup battery life by shortening coil dwell time when running on the
backup battery. Time is adjustable but don’t go too low, or the engine can misfire. Also
as the main and backup batteries weaken, spark will weaken so care must be taken
not to shorten the dwell time too much. Less that 2.8mS could be risky. Misfires can
occur at high throttle if dwell time is too short. Also, coils not supplied by SDS may have different dwell time
requirements, so if you’re running an uncommon coil pack, this setting may be different from the 2.8mS default.
Adjust this when doing a Battery Test run and see what the limit is when lowering the setting, but raise the setting
back to a higher setting than minimum. Best tested at full throttle.
Ignition Off Setup
On installations where there is an aircraft type keyswitch
or other kill-switch wired to the CPi2, set this to EXT
OFF. Setting to EXT OFF will disable the IGNITION OFF
–1 KEY window, which could prevent accidental shut
down of the ignition and engine. If there is no kill switch then set this to KEY –1, then the Ignition Off window can kill
the ignition to shut down the engine.
