IO-390-D Series Engine Maintenance Manual
12-30
© 2020 Avco Corporation. All Rights Reserved
Page 98
March 2020
IO-390-D Series Engine Maintenance Manual
Table 2
EIS Troubleshooting Guide
Problem
Problem Isolation
Probable Cause
Corrective Action
Unable to
time ignition
to engine
(Cont.)
Unable to verify #1 cylinder @ TDC
#1 cylinder not @ TDC
Verify location of engine #1 cylinder.
Turn engine to #1 cylinder TDC, reinstall
ignition unit
Engine runs
rough
Isolate EIS
ignition
causing
roughness
Ignition verified
as correctly timed
to engine #1
cylinder TDC
Verify all
spark plugs
are firing
using CHT
Verify
ignition
unit is
configured
correctly
to engine
base
timing
Ignition harness wires
connected to incorrect
spark plugs
Check routing of harness wires
Internal ignition fault
Contact Lycoming customer support
Ignition
unit is not
configured
correctly
to engine
base
timing
Ignition unit not
configured correctly to
engine base timing
Reinstall ignition unit in accordance with
installation instructions
Various
spark plugs
are not
firing
Single
spark plug
not firing
Bad spark plug or
ignition harness
Replace spark plug or ignition harness
Pair of
spark
plugs not
firing
(1&2,
3&4,
5&6)
Internal ignition fault
Contact Lycoming customer support