Lycoming IO-390-D Series Maintenance Manual page 123

IO-390-D Series Engine Maintenance Manual
Table 2 provides troubleshooting guidelines for applicable EIS.
Problem
Engine runs Ignition
with higher verified as
than normal correctly
cylinder head timed to
temps. engine #1
cylinder TDC
Unable to verify ignition correctly timed to engine #1
cylinder TDC
Unable to #1 cylinder
time ignition verified @
to engine TDC
© 2020 Avco Corporation. All Rights Reserved
March 2020
IO-390-D Series Engine Maintenance Manual
EIS Troubleshooting Guide
Problem Isolation
Verify ignition Engine baffling
unit is configured deficiencies
correctly to
Verify correct engine
engine base
baffling
timing
Ignition unit is not configured correctly to
engine base timing
LED blinks rapidly (12 times per second)
LED timing light 4 cylinder engine
on (solid) but
unable to find the
point when the
6 cylinder engine
LED goes off
TDC marker point
All engines
LED timing light Ignition unit grounded
continuously off to engine
Ignition unit not
grounded to engine
Table 2
Probable Cause
Internal ignition fault
Insufficient engine
cooling
Ignition unit not
configured correctly to
engine base timing
Internal ignition fault
Ignition not timed to
engine correctly
Timing gear installed
upside down on ignition
unit
Timing gear tooth
skipped over engine gear
Turning ignition shaft too
rapidly
No power at timing
terminal
Insufficient case contact
for ground or engine not
grounded to airframe
Insufficient case contact
for ground
Corrective Action
Contact Lycoming customer support
Correct baffling deficiencies in
accordance with OEM specifications
Reinstall ignition unit in accordance with
installation instructions
Contact Lycoming customer support
Reinstall ignition unit in accordance with
installation instructions
Remove timing gear from ignition unit,
rotate gear 180° axially, reinstall ignition
unit
Remove ignition from engine, turn gear to
find the point when the LED goes off
TDC marker point, reinstall ignition unit
Turn ignition shaft slower. Ignition LED
goes off TDC marker point has an easily
missed ½° window
Verify power (8.5 to 30VDC) connected
to timing terminal
Verify ignition unit is grounded though its
case to unpainted surface engine. Verify
engine is grounded to airframe.
Ground ignition unit case to unpainted
surface of engine
12-30
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