Edited by WisdomAugust at 2017-12-13 14:12
Secondary ignition waveform analysis
Now, you won’t be needing to scope too much secondary ignition anymore, but some vehicles still use ignition wires. And when the mood strikes you to scope secondary ignition, keep in mind that secondary waveforms look a lot like primary waveforms.
Can you tell the difference between the secondary and primary waveform? The reason this is so is because primary ignition directly affects secondary. In the below waveform Channel A is Primary Ignition and Channel B is Secondary Ignition. They both look very similar except for the dwell section.
For this reason if an ignition primary originates on the primary, it will askew your secondary waveforms. Be sure to scope secondary ignition AFTER confirming primary ignition is good.
This is how secondary waveforms should look. 1. The coil begins charging up full of current. The oscillations are magnetic interference from a working ignition coil. 2. During the dwell period, voltage builds very slowly. 3. The ignition coil unleashes all of its current into the secondary side of that same coil. Voltage skyrockets. Instantaneously the spark jumps the spark plug gap. 4. Spark line should be relatively high in voltage. Its duration is the firing time. 5. Oscillations happen when there is not enough power to continue the spark and any remaining power is squeezed out.
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