GxT Ferret 63 DIAGNOSTIC ENGINE ANALYZER - Manual (Page 19)

BURN TIME SLOPE
Slope tells about the fuel mixture at the end of burn time.
Lean makes the voltage rise (plus) and rich makes it fall
(minus) during the end of the spark.
When a spark has a slope more than 20 counts over the
overall averages and burn time is short, look for a wide
or worn plug gap. If burn time is normal, the cause may
be: a lean fuel mix, a manifold or EGR leak, a low fuel
pressure regulator, or a cylinder valve leak.
When the slope is 20 counts less than the overall aver-
age, look for a richer fuel mix or high resistance spark
wire. On multiport fuel injection engines a leaking injector
will be likely to cause a consistently lower slope than the
other cylinders.
Most engines have slopes in the +30 to -30 range. Good
engines usually have all the values within about 10
counts either side of average. Keep in mind that these
readings are highly variable because they are affected
by the fuel burning. The key is to look for the obviously
different cylinders.
When PRINT DATA is
used the Spark Burn
test data will be printed
and graphed. The graph
spans "MIN" to "MAX"
and has a mark at the
"AVE" data value. The
readings are in firing or-
der from top to bottom.
DIAGNOSTIC MESSAGES
Messages are caused by odd combinations of Spark
Burn Time and Slope. Follow up on these suggestions
with visual inspection and component testing.
It is recommended that messages about multiple cylin-
ders be ignored until single cylinder messages have been
looked into. Since most of the messages are based upon
comparisons of each cylinder to the others, it is possible
that one bad cylinder may make the others look relatively
out of line. Additionally, an open arcing spark plug wire
can cause test effects that trigger many messages. Re-
test after each repair.
The following displays pick out individual cylinders from
the firing sequence and suggest possible problem
causes:
Additional problem categories include:
WIRE RESISTANCE High, PLUG Foul ? ,
CAP Track ?, GAP Wide ? , FUEL Lean?
The next messages relate to all spark plugs together:
Plug GAP Narrow?
Shorted
?Coil - Distributor?
?Coil-Distributor?
or Plugs: Wide GAP?
Fuel Rich?
Additionally if Ignition Energy is very low it will show:
COIL PRIMARY DRIVE Bad?
Note, if the Spark Pickup is not working the spark plug
data will not be available. A message will show:
no SPARK PICKUP Signal
Diagnostic messages from this analyzer are based upon
a range of Burn Time that is typical for most engines.
There are however, some engines which are designed
differently and have performance ranges that may ap-
pear to be abnormal to the analyzer so that it will produce
messages indicating a possible defect. Compare the
measured values to readings from similar engines or
specifications from the engine service manual to confirm
that the messages apply.
-17-
GAP Narrow
Seq. # 5 6
BURN
TIME
BURN
TIME
FALLING
SLOPE
(Minus)
RISING
SLOPE
(Plus)
COIL PRIMARY WAVEFORMS
SPARK -20 -18 - 5 -11
Slope msg 9 6
------------------------
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