Lycoming IO-390-D Series, Maintenance Manual

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IO-390-D Series Engine Maintenance Manual
© 2020 Avco Corporation. All Rights Reserved 12-30
March 2020 Page 97
IO-390-D Series Engine Maintenance Manual
Table 2 provides troubleshooting guidelines for applicable EIS.
Table 2
EIS Troubleshooting Guide
Problem Problem Isolation Probable Cause Corrective Action
Engine runs
with higher
than normal
cylinder head
temps. Ignition
verified as
correctly
timed to
engine #1
cylinder TDC Verify ignition
unit is configured
correctly to
engine base
timing Engine baffling
deficiencies Internal ignition fault Contact Lycoming customer support
Verify correct engine
baffling Insufficient engine
cooling Correct baffling deficiencies in
accordance with OEM specifications
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
LED blinks rapidly (12 times per second) Internal ignition fault Contact Lycoming customer support
Unable to verify ignition correctly timed to engine #1
cylinder TDC Ignition not timed to
engine correctly Reinstall ignition unit in accordance with
installation instructions
Unable to
time ignition
to engine #1 cylinder
verified @
TDC
LED timing light
on (solid) but
unable to find the
point when the
LED goes off
TDC marker point 4 cylinder engine Timing gear installed
upside down on ignition
unit Remove timing gear from ignition unit,
rotate gear 180° axially, reinstall ignition
unit
6 cylinder engine Timing gear tooth
skipped over engine gear Remove ignition from engine, turn gear to
find the point when the LED goes off
TDC marker point, reinstall ignition unit
All engines Turning ignition shaft too
rapidly Turn ignition shaft slower. Ignition LED
goes off TDC marker point has an easily
missed ½° window
LED timing light
continuously off Ignition unit grounded
to engine No power at timing
terminal Verify power (8.5 to 30VDC) connected
to timing terminal
Insufficient case contact
for ground or engine not
grounded to airframe Verify ignition unit is grounded though its
case to unpainted surface engine. Verify
engine is grounded to airframe.
Ignition unit not
grounded to engine Insufficient case contact
for ground Ground ignition unit case to unpainted
surface of engine