distributor ignition system waveform

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distributor ignition system waveform

Postby eric989 » Fri Dec 07, 2012 3:16 pm

Hi all,

The waveform is captured from a distributor ignition system. Ch A is from cylinder 1 plug lead, Ch B is from distributor King/main lead.

We can see from Ch A that the cylinder 1 have a ignition fault , its burn line is not almost horizontal, and have a bad coil oscillation. But the waveform for cylinder 1 on Ch B is very good, its burn line is almost horizontal. Could somebody here explain why?

Many thanks advance.

蓝色是一缸信号,红色是主高压线信号.psdata
blue from cylinder 1, red from King lead
(895.26 KiB) Downloaded 227 times
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Re: distributor ignition system waveform

Postby Autonerdz » Sun Dec 09, 2012 8:11 pm

This is because the plug wire only shows the activity after the rotor. Much of the secondary activity you accustomed to seeing takes place before the rotor, including the coil oscillations.
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Re: distributor ignition system waveform

Postby Avdr » Mon Dec 10, 2012 5:46 pm

Autonerdz wrote:This is because the plug wire only shows the activity after the rotor. Much of the secondary activity you accustomed to seeing takes place before the rotor, including the coil oscillations.


But wouldn't that mean that much of the energy has already been lost from the coil before the rotor arm lines up with the particular plug lead?
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Re: distributor ignition system waveform

Postby Autonerdz » Mon Dec 10, 2012 6:34 pm

But wouldn't that mean that much of the energy has already been lost from the coil before the rotor arm lines up with the particular plug lead?


Not sure I understand the question. The energy is released once the secondary current begins to flow. This does not happen until the gap requiring the highest KV is overcome and the spark is lit. There is no activity on the plug wire until the current bridges the rotor gap. Then the activity stops when the current stops. The residual energy oscillations remain upstream from the rotor and are not seen on the plug wire.
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Re: distributor ignition system waveform

Postby Avdr » Tue Dec 11, 2012 8:32 pm

Autonerdz wrote:
But wouldn't that mean that much of the energy has already been lost from the coil before the rotor arm lines up with the particular plug lead?


Not sure I understand the question. The energy is released once the secondary current begins to flow. This does not happen until the gap requiring the highest KV is overcome and the spark is lit. There is no activity on the plug wire until the current bridges the rotor gap. Then the activity stops when the current stops. The residual energy oscillations remain upstream from the rotor and are not seen on the plug wire.


Sorry - had a blonde moment there, I had overlooked the fact the rotor arm isn't actually connected to the plug wire, as it passes by. The moment I read your reply it all came back to me.

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