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Secondary or primary "nose" (Read 5,085 times)

MarkW

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Secondary or primary "nose"
Mar 19^th, 2004 at 11:34am

There is a thread in the Techs section entitled: "Secondary Burn Voltage"

Per Mac VandenBrink's
www.autonerdz.com/downloads/copman.pdf

could someone pls further expand on what a normal secondary or primary "nose" should look like (the first peak to the right of the spark line), on an electronic ignition, single distributor system should look like.

In particular, if the nose frequently/intermittenly drops down to almost the same amplitude as the spark line (while the spark line essentially remains flat, but jaggies can be invoked), does that infer that spark energy is being shunted somewhere outside the cylinder?

Should nose's amplitude remain fairly consistent (IIRC, at least 1 KV - 2 KV above the spark line for secondary, and at least ~20 V above the spark line on the primary), when healthy/normal (sometimes giving the appearance of a shortened burn time, i.e, the spark line again is essentially flat, but the nose "pulls" the spark line slope up as HCs burn out ?

Thank you,
Mark Welch

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datec

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Re: Secondary or primary "nose"
Reply #1 - Mar 20^th, 2004 at 5:52pm

The "NOSE" indicates that there is residual energy left over after the plug stops firing. Absence of the nose indicates there is no gap
With a distibutor type ignition, there is always a gap even when the plug is fouled out.
When the clip (secondary lead) is located at the Coil Wire (King wire), there is more energy at that point, resulting in greater oscillations. When the clip is moved to the plug wire, the energy (evidence is oscillation amplitute) is greatly reduced. Note a DIS ignition with very small oscillations
The greater the gap the more residual energy is left over. Pull a plug wire to create a small gap and you will see a direct relationship between gap and amplitute.

What is normal? The objective is to fire the plug. Any external energy is energy loss.
Conclusion: The lower the residual energy, the more firing time, the better chance for complete combustion.
Zero amplitute means that all the energy is drained to ground potential. In case of a distributor this wil never happen.

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MarkW

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I love YaBB 1G - SP1!

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Re: Secondary or primary "nose"
Reply #2 - Mar 23^rd, 2004 at 2:23pm

Thanks datec. I've been thinking of this a bit the last few days. I may have to reconsider what I originally thought was a normal spark line burn duration, as am seeing (what I think is) a lot of nose amplitude variation, on both secondary and primary patterns, and possibly incomplete/inconsistent combustion (or at least less than optimum). I need to further explore some other abnormal findings, as well

It seems like the nose amplitude should be fairly stable (probably with some moderate variation, but I don't yet have an eye for what's too much vs normal). Wish I had a DSO to post a pic.

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Tom Roberts Autonerdz Administrator Picogroup Offline Autonerdz Founder Posts: 8,595 Olympia Washington USA Gender:	Re: Secondary or primary "nose" Reply #3 - Mar 23^rd, 2004 at 9:16pm Hi Mark, Quote: Wish I had a DSO to post a pic. I can help you with that. http://www.autonerdz.com/picokit.htm
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