Scope and Multimeter Operations Ignition Scope
141
9.14.2 Ignition Waveform Reference
The following ignition waveform information is intended as general theory reference
only, using distributor type ignition illustration examples.
Ignition waveforms have three basic sections (Figure 9-74). An ignition event
begins with a firing line at the left of the screen, continues through the intermediate
and dwell sections, and ends with the beginning of another firing line at the right
edge of the screen.
1— Firing section
2— Intermediate section
3— Dwell section
Figure 9-74 Sample ignition waveform
The Ignition Cycle
Waveforms have specific points that show important information when checking an
ignition system. A complete ignition cycle of a cylinder runs from primary current
switching on to the next primary current on event. Therefore, the description and
explanation of the waveforms begins just before primary current switches on. See
following page for description of image callouts.
Figure 9-75 Sample ignition cycle
1 2 3
1 2 3
Primary WaveformSecondary Waveform
1. Start of ignition
2. Spark line
3. End of ignition
4. Coil oscillations
5. No current in the primary coil
6. Primary current turns on
7. Start of primary current
8. Current limiting
9. Primary current turns off
2
8
2
8
Primary WaveformSecondary Waveform
134 5 6 7 9
1 3 4
5 6
7
9
To Next Page
Loading...
Need help?
General
