GxT Ferret 63 DIAGNOSTIC ENGINE ANALYZER - Manual (Page 20)

“POWER BALANCE” KEY
This test measures each cylinder's contribution relative to
the others by turning off the spark plugs
one at a time and measuring the drop
in RPM. The more decrease seen, the
more a cylinder must have been con-
tributing. A comparison of an engineʼs
entire set of readings is necessary be-
cause of engine to engine variations. If a cylinder shows
only 1/3 of the drop of the average cylinder it should be
checked further with the other analyzer tests. Low power
cylinder problems are associated with spark plugs and
wires, piston rings, valves and valve springs, vacuum
leaks, fuel unbalance, head gaskets, and EGR problems.
If a cylinder test produces a higher RPM it may be from
crossed spark plug wires, an open intake valve, leaking
EGR, or an engine computer effect.
The test relies upon steady timing, fixed air-fuel feed and
a constant amount of engine drag during the test to make
valid comparisons between all of the cylinders.
A steady drag on the engine can improve the test results.
Turning the heater fan on high and headlights on bright is
usually the best method. Particular attention should be
directed to eliminating loads that can turn on or off in the
middle of the test such as the air conditioner compressor
and radiator fan motor.
Operating the engine above the controlled idle RPM will
minimize the effects of idle compensators and put the
engine at a smoother operating point. RPMʼs of 1000 to
2500 are suitable for the test. Listen to the sound of the
engine as suppression is applied. The initial RPM drop
tells if power is strong.
On non-computerized engines the timing, fuel mix and
idle setting do not vary with time. However, active control
systems may have to be put in open-loop mode to keep
the timing and fuel mixture fixed.
The idle speed motor may have to be unplugged if the
test is done at idle. Disconnecting the coolant tempera-
ture sensor will usually cause the computer to operate in
open-loop fuel control as if the engine were cold. Where
the oxygen sensor is easily reached it can be unplugged
to lockup the fuel control. Timing can usually be fixed by
disconnecting the MAP sensor hose, or as on Fords, pull-
ing the timing test plug. EGR valves should be disabled
by removing and plugging the vacuum hose to the valve.
On some engines there is a running test mode that can
be set through the diagnostic connector which lets the
test run without interaction effects. Refer to the engine
service manuals for details.
After the test, carefully restore the disengaged parts.
Service codes may have to be cleared, but they will usu-
ally clear automatically after 50 to 100 starts.
The results of this test, if compared to the Cranking Amps
and Spark Burn tests, can provide additional clues to the
cause of poor cylinder performance.
A manual cylinder selection version of the test is pro-
vided to check for engine noise changes when power is
removed from a particular cylinder.
When PRINT DATA is used the Power Balance test data
will be printed and graphed. The % RPM graph shows
the percentage drop by cylinder. Weak cylinders will
show up as a very short bar. Strong cylinders will show
up as a long bar.
TEST
PROCEDURE
BASIC TEST
You should have com-
pleted the analyzer
SETUP Steps, and used
IGNITION PRIMARY
to check the leads to
engine hookup. Press
POWER BALANCE to
begin. The following
screens will appear:
SENSOR
TEST
02 TPS
SETUP AMP ZERO SELECT MESSAGE
PRINT
DISPLAY
PRINT
AUTOTEST
CHARGING
STARTING
AMPS VOLTS
IGNITION
PRIMARY
COIL MODULE
DWELL VARIATION
AUXILIARY AUXILIARY PER CYLINDER
CRANKING
ANALYSIS
COMPRESSION
BAT. STARTER ALT.
POWER
BALANCE
% RPM DROP
AUTO MANUAL
PER CYLINDER
SPARK
BURN
SECONDARY
MSEC SLOPE
PER CYLINDER
HARD
START
IGNITION VOLTS
AUXILIARY
FUEL
INJECTION
MSEC, % DUTY, HZ
AUXILIARY
START
PAPER
ADVANCE
SUPRESSION CYCLES
CYLINDER
SEQUENCE
RPM
END
RPM
CYCLE 3
RPM START
1 2 3 4
* * *
RPM DROPS FROM SPARK SUPPRESSION
" * " shows recovery times
-18-
WARNING
This test causes unburned fuel to be passed into the
exhaust. Catalytic converters burning this fuel will
become hotter. Repeating the test frequently may
cause excessive heat under the car.
------------------------
ENGINE DATA REPORT
------------------------
====CRANKING HISTORY====
SEC RPM BATT AMPS
1 13.33 151
2 326 11.88 129
3 306 11.57 122
4 301 11.35 116
5 300 11.17 114
7 292 11.03 113
9 291 10.85 112
11 289 10.76 112
13 288 10.70 112
15 288 10.66 111
------------------------
CRANKING VOLTS 10.66
CRANKING AMPS 111
------------------------
CRANKING RPM 288
ALTERNATOR AMPS 38
------------------------
BATTERY CCA EST. 487
RECOVERY SECONDS 23
------------------------
==SPARK BURN ANALYSIS==
RPM IGEGY BATTERY
772 43 14.13
IN FIRING ORDER
MIN AVE MAX SLOPE
0.9 2.0 2.1 10
1.1 2.0 2.2 10
1.0 2.0 2.1 15
0.9 2.0 2.1 17
0 1 2 3 4 MS
BURN TIME RANGE
====IGNITION PRIMARY====
850 RPM BAT 14.01
OSC 2 IGEGY 43 DRVR 0.8V
847 RPM DWL 3.6MSEC
DWL 0.3 VARIES TMG 4.8
==== POWER BALANCE ====
ORDER START END %DROP
1 852 767 10
2
849 764 10
3 858 764 11
4 848 763 10
- 0% 10 20 30 +
% RPM DROP
=ELECTRONIC COMPRESSION=
ORDER AMPS %MAX %LOW
1 120 99 1
2 120 99 1
3 119 98 2
4 121 100 0
80 90 100%MAX
% OF PEAK AMPS CRANKING