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Lean of Peak (LOP) Operation
Pressing the LOP key will activate the function in the EM-6 ecu and will advance ignition timing and lean
fuel depending on the settings. Note that LOP will be enabled but for the LOP ignition advance and Fuel
Leaning to occur a two conditions must be met:
1. Manifold Pressure must be equal or less than LOP MAX MANIFOLD PRESSURE setting.
2. Engine RPM’s must be 1500* or higher, (not adjustable).
There is no need for LOP at low engine RPM”s like idle or taxi conditions. It is best to only activate LOP
after takeoff when in cruise conditions. Activating LOP on the ground may make the engine lean out to
where it loses power during taxi or runup and you may think there is an engine problem.
* For high revving engines (auto engine conversions & geared), SDS is set for 250 rpm increments, the
minimum rpm is 2200.
LOP CONTROL
Also note that if using the PIN13 setting here and your own toggle switch to activate LOP then the LOP
key on the Design1 programmer will not function, but the blue LED will light up with your LOP switch
turned On when the PIN13 input sees 6 volts or higher.
LOP IGNITION ADVANCE
This window sets the amount of ignition advance when LOP is activated. Usually no more than about 5
or 6 degrees should be entered here. Just enough to smooth out LOP running of the engine. Fuel only
SDS systems wont use this window since these systems don’t control ignition timing.
LOP LEAN FUEL DISABLED or Use Percentage or Use Target AFR
Allows an easy way to turn off leaning of fuel mixture rather than having to change the percentage (or
LOP AFR target) setting. Use + button to select.
LOP Lean Fuel Amount
Traditional method was to Lean fuel by a set percentage amount which does work very well. With the
EM-6 if you have a wideband O2 unit connected to SDS ecu, then you can try the LOP Lean Fuel Target
setting and the SDS will chop the fuel pulse initially, then trim or add fuel to achieve the Target setting for
LOP. This does rely on the wideband O2 signal so if the wideband O2 has a problem this is going to
cause LOP AFR to be wrong. Trim percent in LOP AFR is limited to +/- 15%. Do not select Use AFR
target without having the wideband connected to SDS! Do Not use the Target AFR setting with Leaded
fuel.
Reminder: If you have a 6cyl dual ecu be sure to duplicate these LOP settings in the Backup ECU since
it is running injectors 4,5,&6 on the engine!
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