TM 9-2320-387-24-l
1 2-46. STEIICE-R TEST PROCEDURES
(Cont’d)
COMPRESSION UNBALANCE
TEST #14
Description:
This procedure compares the compression
between the highest and lowest cylinders and
displays the unbalance in percent. Test requires
DCA hookup only.
Typical Applications:
Check compression unbalance of engine with
VTM powered from battery of vehicle being
tested.
Test Procedure:
1. Set up engine to prevent starting by disconnecting
wire 54A. Stop engine. Shut off fuel before
cranking. Crank engine without fuel for 5 seconds
to clear fuel from cylinders.
2. Set TEST SELECT switches to 14.
3. Press and release TEST button.
4. Wait until GO appears on display before
proceeding.
5. When GO appears, crank engine. Display will
change to ---- while engine is turning.
6. When OFF or E013 appears, stop cranking.
7. If OFF appears, wait for message to appear.
(A) The number displayed will be the percent
unbalance between the highest and lowest cylin-
ders. A number above 25 is a failure.
(B) If GO appears, repeat from step 2.
(C) A FAIL message usually means compression
is too far unbalanced to measure with STEIICE.
Pre-Test Procedures:
Run confidence test. Warm up engine
to operating temperature.
Run first-peak series tests 72, 73.74,
75.
Possible Error Messages:
E006 VTM doesn’t detect battery
voftage.
E013
VTM cannot use data
received.
E027
Error in entry of compression
unbalance constants.
E032
Vehicle’s cranking speed is
varying too much for a
compression unbalance
measurement..
NOTE:
If E013 appears, test data cannot be
anafyzed because of weak batteries or
interrupted cranking during test.
Correct problem and repeat from
step 2.
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