EMS Monitoring Functions
6-2
EMS-D10 Pilot’s User Guide
To exit the Lean mode, reactivate the main menu and press the LEAN button; the EGT/CHT display then returns to its
normal state.
For best results, lean carefully by making small adjustments and allowing some time for temperatures to stabilize before
leaning further. In addition to the EGT temperatures, you can also watch the fuel flow rate and CHT temperatures.
Carefully read and follow your engine manufacturer’s leaning recommendations for best performance.
On some engines, when given the proper set of inputs, the EMS can also calculate percent power and lean-of-peak or
rich-of-peak operation in real time. To do this, the EMS needs access to OAT, MAP, RPM, Altitude (from EFIS or
EMS) and fuel flow, and needs to be monitoring an 8.5:1 compression ratio engine. This information is based on
Lycoming and Continental power charts, is updated in real time, and is displayed near the manifold pressure gauge. The
leaning information has three states, LOP, ROP, and PK (Peak). This information can be used to determine when it is
safe to lean the engine, and if the current operating state is near peak or not. While this information is based on published
charts, you should independently verify via manual leaning that this data matches your install and engine.
Detonation Characterization
Detonation is defined as the uncontrolled explosion of the fuel/air mixture. It occurs when the anti-knock rating of the
fuel is lower than required by the pressure and temperature generated during engine operation. Using a fuel octane
number less than that required, or over-leaning the engine can result in detonation and induce engine damage. Leaning
too aggressively can leave little margin between normal combustion and detonation. Any defect like a bad spark plug,
partially blocked fuel injector nozzle or intake manifold leak combined with a minimum margin can result in detonation
and engine damage. One key characterization of detonation is lower EGT temperatures with corresponding higher
cylinder head temperatures.
