Altronic CPU-95 Operating Instructions Manual page 33

11.5 The above user programmable thresholds need to be adjusted based on the
type of coil being used and on the operating characteristics (specifically,
voltage demand) of the engine. There are known differences between various
types of Altronic coils, and slight variations are normal between coils of the
same type. In order to maximize the usefulness of the cylinder spark reference
number, it is recommended that all coils be of the same type and vintage
(production date). This will aid greatly in detecting variations in one cylinder vs.
the general trend in the engine. The typical ranges to be expected in normal
operation with new spark plugs are:
Older 501061 (blue) coils:
Current 501061 (blue) coils:
11.6 The indicated thresholds were designed to be adjustable so that the user
can customize these diagnostics to fit the specific needs of each engine. It
will take some testing and adjustment to obtain thresholds that optimize the
use of these features. For maximum benefit, the spark reference number for
each cylinder should be recorded at normal operating load with new spark
plugs installed and then monitored over a period of time for changes. The HI
SPARK VOLTAGE alarm level should be set (typically) at 180 initially and can
be adjusted as experience dictates. A gradual increase in the spark reference
number is expected over time as the spark plug electrodes erode.
11.7 In addition to the diagnostic flags, the reference numbers can also be used for
predictive purposes:
A. As the numbers increase toward the preset HI SPARK VOLTAGE threshold
(SEE SECTION 12.3), the operator knows that a change of spark plugs should
be scheduled. With this information, this function can be determined on an
actual need basis rather than a predetermined schedule. Also, unexpected
engine misfiring or shutdowns can be avoided by tracking the reference
numbers on a routine basis.
B. The reference numbers can provide an early warning of a difference in
operation in a given cylinder(s). A reading higher (or lower) than the other
cylinders, when such a difference is not normally present, tells the operator of
a potential problem; this allows further troubleshooting and evaluation to take
place before an unexpected operational problem develops.
(SEE SECTION 12.5, 12.6.)
11.8 Other Information regarding the spark reference number:
A. The spark energy setting has only a small effect on the reference number if
the spark plug fires correctly. Therefore, the high and low voltage thresholds
should hold across the spark profile settings if the spark plugs continue to fire
correctly. On the other hand, a worn plug may not fire consistently on spark
profile setting E1 but will on spark profile setting E2.
B. The spark reference number is designed to work with one coil per output.
Where two coils are connected to the same primary lead, the number will tend
to be an average of the conditions at the two spark plugs. While some of the
benefits of the spark reference number can still be realized, the usefulness
of the number in detecting deviations between cylinders (alarm levels) will be
reduced.
CPU-95EVS OI 7-13
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