J.P. Instruments EDM-960

For Your Safe Flight Page | 60
Troubleshooting the EDM-960
Common Misapplications
Problem
Situation
Correction
Display freezes or
may be incorrect
A power transient
could cause the
processors to
malfunction
Recycle the power to
the EDM
Lean Find finds a
“peak” too soon
Failure to pre-lean
before performing
Lean Find or
stopping while
leaning
Continue to lean without
stopping
Leaning too slowly
Lean more rapidly
Peak not found
during Lean Find
Lean Find not
activated or stopping
while leaning
Lean at the speed of
approximately 10°F per
second
Off-scale EGT
columns, too high
or low
Off-scale EGT
column readings.
EDM in the
Normalize view (blue
scales)
The higher sensitivity of
the Normalize view can
quickly go too high or
low off-scale with only
small changes in EGT.
First cylinder to
peak is not the
hottest
This is normal. The first to cylinder peak is not
necessarily the hottest
EGTs rise during
single magneto
check
This is normal, due to incomplete combustion
persisting longer
EGTs not uniform
during low power
operation
This is normal. Fuel and air distribution is not
optimal at low power settings
Diagnostic Testing on Startup and During Flight
When your EDM is first turned on the unit performs several tests on
internal components, calibration and integrity of the probes. Typically,
alarms are disabled until the engine has been started.
During flight, probes are constantly checked for inconsistent or
intermittent signals. A faulty channel or probe encountered during start-up
or during flight will be deleted from the sequence, producing a missing
column or blank digital data.