Scope and Multimeter Operations
Ignition Scope
137
Trigger (Ignition Scope)
Trigger Setup (
) allows you to:
–
Change the triggered cylinder (Single Cylinder Mode only)
–
Adjust the detection sensitivity to cylinder firings
About Detection Sensitivity
The sensitivity adjustment is primarily used to fine tune the ignition signal into
a viewable pattern. The “Vertical” slider is used to raise or lower the cylinder
firing detection sensitivity. Adjusting the sensitivity can be useful when:
- When the scope is intermittently detecting cylinder firings. If this occurs,
lower the setting to achieve a viewable pattern.
- When the scope is detecting noise or other events. If this occurs, raise the
settings to achieve a viewable pattern.
It is important to note that detection sensitivity does not function like a
standard scope trigger that triggers at a set level. Adjusting the sensitivity
high (10-20kv), assuming it will trigger at the firing kV and display a pattern
is incorrect.
The sensitivity setting is designed to detect and adjust the viewable pattern
of an ignition waveform. A good starting point for most systems is 2.0 kV,,
however this can vary depending on the pickup. In most cases, start at the
average spark kV of the system (typically 2 kV) and then make adjustments
(high/low) as needed to find and display a viewable pattern. The following
general rules of operation apply:
Higher
= less sensitive
Lower
= more sensitive
Setup Notes:
- With Wasted Spark ignition systems, the sensitivity level setting only
displays on Channel 1, but the setting applies to both channels.
- Unless you are having problems detecting cylinders, a sensitivity setting
of 2.0 kV is optimal for most ignition systems.
- When a cylinder firing is not detected because it is either firing too low to
be detected at the current setting or is not firing at all, a blank space
displays in the on-screen pattern. To verify a missed cylinder firing, lower
the sensitivity setting to verify that the cylinder is firing, but firing too low
to be detected at the current sensitivity setting. If a cylinder is not firing at
all, the blank space on the graph will remain.
Figure 9-67
If using a time based sweep setting, the Trigger Setup (
) allows you to:
–
Change Auto / Manual trigger mode
–
Trigger from a Cylinder or None
–
Adjust the trigger vertically on the KV scale using the slider (right side)
–
Adjust the trigger horizontally on the sweep scale using the slider (bottom)
Figure 9-68
