6 PERFORMANCE DIAGNOSTICS 249
If TDC rpm is greater than rpm 30 degrees after TDC,
the EST will disp la y 0.
If the test value for a power cylinder is 0, the cylinder
is suspect.
If the test value for a power cylinder is significantly
below 15 rpm, the cylinder is suspect.
Test value 5 for cylinder 1 indicates a suspect cylinder.
Test value 0 for cylinder 6 indicates a suspect cylinder.
When the Relative Compression test is done, the EST
indicates, stop cranking the engine, and will display
test values.
Test data displayed in this test should be compared
with data collected from the Injector Disable test.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
Procedure
WARNING: To avoid serious personal injury,
possible death or damage to the engine or
vehicle, read all safety instructi on s in the “Safety
Information” section of this manual.
NOTE: Batteries must be fully charged before doing
this test. If multiple tests are necessary, use a
battery charger during this test; battery drain can be
extensive.
Figure 325 Relative Compression Test
NOTE: Read and be familiar with all steps and time
limits in this procedure before starting.
1. Select Diagnostics from the m enu bar.
2. Select Relative Compression Tests from the drop
down menu.
3. Follow the messages at the bottom of the window.
• Turn the ignition switch to ON.
• Select Run.
WARNING: To avoid serious injury,
possible death, or damage to the vehicle –
comply with the following: After clicking Run,
turn the ignition switch – within 5 seconds –
to crank the engine; if not done in 5 seconds,
the EST will cancel the test and the engine
will start.
• Crank engine for 15 seconds. (Another
message may read Stop Cranking.) Do not
turn ignition switch to OFF. If the switch
is turned to OFF, test results will be lost.
NOTE: If test results are identical to previous test
results, the current test failed and the previous
results were displayed.
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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