J.P. Instruments EDM 740 Pilots Guide - Manual (Page 6)

Page 6 Engine Data Management
Engine Data Management
The EDM Engine Data Management system is the most advanced and
accurate piston engine-monitoring instrument on the market. Using the
latest microprocessor technology, the EDM will monitor up to twenty-
four critical parameters in your engine, four times a second, with a
linearized thermocouple accuracy of better than 0.1 percent or 2 F°.
As your built-in flight engineer, the EDM is constantly “red line”
checking: all critical parameters are automatically checked four times a
second, regardless of the current display status. Leaning is accomplished
quickly and automatically using the LeanFind
 procedure. With the
EDM, it is now possible to have substantially more diagnostic
information available to you in a timely and usable manner.
Benefits of Proper Mixture Control
 Improved engine efficiency  Reduced maintenance costs
 Greater fuel economy  Reduced operating costs
 Smoother engine operation  Proper engine temperatures
 Longer spark plug life  Reduced engine vibration
JPI Probes
Temperature information
processed by the EDM is captured
by fast response grounded
JPI
temperature probes that accurately
measure small temperature
changes—as small as 1°F—that
routinely occur during mixture
adjustment.
Temperature and Mixture
In a piston engine only a small portion of the energy from combustion
produces movement of the piston during the power stroke. The majority
of energy passes into the exhaust pipe as hot gasses. By monitoring the
temperature of these exhaust gasses you will have an indication of the
quality of the combustion process. Low compression, non-uniform fuel
distribution, faulty ignition, and clogged injectors diminish the
efficiency of the combustion process that generates power. From the
cockpit you can adjust the fuel/air ratio by a process called leaning.
Retarding the mixture control changes the fuel/air ratio and hence affects
the Exhaust Gas Temperature (EGT).
CHT probe
EGT probe
cylinder
head
exhaust
manifold