3 DIAGNOSTIC SOFTWARE OPERATION 85
Injector Disable Tests
NOTE: The Injector Disable tests can only be
done with the EST; MasterDiagnostics® software
is required.
The Injector Disable tests allows the technician to
shut off injectors to determine if a specific cylinder is
contributing to engine performance. Injectors can be
shut off one at a time, alternative cylinders at a time
or alternative cylinders plus one.
Alternate cylinders are every other cylinder in firing
order.
Firing order: 1-5-3-6-2-4
When all c ylinders are active, the contribution of
each cylinder is 17% of its overall effect to maintain
governed speed. When three cylinders are shut off,
contribution of each remaining cylinder is 33% of
its overall effect to maintain governed speed. The
technician should monitor fuel rate and engine load.
NOTE: The Relative Compression test should be
done after doing the Injector Disable test to distinguish
between an injector or mechanical problem.
NOTE: Before doing the Auto test or Manual test for
injector disable, make sure Performance Diagnostics
tests 1 through 10 were completed and the following
conditions are maintained:
• Make sure acc essories are turned off (for
example: engine fan and air conditioning). Items
cycled during this test could corrupt the test
results.
• Maintain engine idle.
• Keep EOT within a 2 °C (5 °F) range from the
beginning to the end of the test. EOT affects
injection tim ing; too much of a change in EOT
temperature could co rrupt the test re su lts.
NOTE: If any injectors are remove d a n d rein stalle d
or replaced, test drive vehicle for 20 miles before
checking for misfire or rough idle.
Automatic Test
The Automatic test is best used when comparing
cylinder to cylinder test data.
NOTE: If MasterDiagnostics® software does not have
the Automatic test (auto run feature), see “Injector
Disable - Manual test - Engine Hot” later in this section
for procedure to compare cylinder to cylinder.
NOTE: Do KOER Standard test before doing this test.
WARNING: To avoid serious personal injury,
possible death or damage to the engine or vehicle
- comply with the following: When running the
engine in the service bay, make sure the parking
brake is set, the transmission is in neutral or park,
and the wheels are blocked.
NOTE: If any injectors are removed a nd reinstalle
d
or replaced, test drive vehicle for 20 miles befo
re
checking for misfire or rough idle.
Figure 87 KOER IDT I6 session
1. While engine is running, se
lect
D_KOER_IDT_I6.ssn from t
he op en
session file window and sel
ect OPEN to open
the session.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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