J.P. Instruments EDM 900 Pilots Guide - Manual (Page 28)

Page 28 Engine Data Management
LeanFind Procedure—General Explanation
Lycoming and Continental established specific restrictions on leaning
that must be followed, such as percent power, climb leaning, and TIT
limits. Lycoming recommends operation at peak of EGT at 75% or
less power only. Continental recommends operation at peak EGT at
65% or less power only. This guide does not supersede specific
recommendations of the engine or airframe manufacturer. It is your
responsibility to know your aircraft’s limitations.
Pre-leaning: The leaning process typically begins with ‘pre-leaning’ to
insure all cylinders are operating rich of peak EGT (note: you can
optionally activate ‘Normalize’ - hold LF until NRM appears - making it
easier to confirm all EGTs decrease). Now enriched the mixture to
achieve a 50° drop on the hottest EGT. Insure that all EGTs decrease.
Wait one minute to allow temperatures to stabilize.
Lean Find-Initiation: Initiate the EDM leaning mode by tapping the LF
button. Note that the EDM displays its current leaning mode
momentarily: ‘ROP’ for operating Rich of Peak or ‘LOP’ for operating
Lean of Peak. Then the current mode will show up in the message bar
white on black, also you will see the alternate mode over the LF button.
You have 10 seconds to chose the alternate mode which will disappear
indicating your chosen mode white on black. To change, simply exit the
mode you are in and re-tap the LF button. The EDM is now waiting for a
15° rise on any EGT (this feature significantly reduces false peaks). Lean
the mixture without pausing to achieve about a 10 deg per second
change. With a vernier mixture control, turn the knob about a quarter turn
every second. With a non-vernier or quadrant mixture control, lean slowly
and smoothly about 1/16 inch every five seconds (note: leaning
accurately with a quadrant system is difficult due to its mechanical
linkage).
Lean Find-Activation: When a 15° EGT rise occurs, LeanFind
activates (indicated by a cylinder I.D. box flashing over the number of the
hottest EGT). Remember: The LeanFind mode is not active until a
cylinder I.D. box is flashing. To show the progress of the leaning
process, the EDM now displays the hottest EGT in the left side of the
digital display and the fuel flow in the right side. This information allows
you to observe the EGT behavior throughout the leaning process.