J.P. Instruments EDM-960

For Your Safe Flight Page | 9
Engine Diagnosis Chart
The following chart will help you diagnose engine problems in your
aircraft (note: only one engine is shown).
Display
Symptom
Probable
Cause
Recommended
Action
TIT ~100°
higher than
EGTs
This is normal
75° to 100°
EGT rise for
one cylinder
during flight
Spark plug not
firing due to fouling,
faulty plug, wire or
distributor.
Enrich mixture to
return EGT to
normal. Have plugs
checked.
EGT Increase
or decrease
after ignition
maintenance
Improper timing:
high EGT 
retarded ignition;
low EGT 
advanced ignition.
Check EGT for
each magneto to
determine any
uneven timing.
Loss of EGT
for one cylinder
and Engine
rough
Stuck valve. Other
cylinders are okay.
Have valve train
checked.
Loss of EGT
for one cylinder
and no digital
EGT and/or
bad probe
message.
Failed probe
or
failed wire harness.
Swap probes to
determine if probe
or wire harness is
bad.