Looking for advice with Snap On Verus and secondary ignition

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2 years 1 week ago #55056 by Joshasta
Hello, Im looking for any pointers on how I can capture a better waveform, and how to better understand what I have captured.I am using Snap On Verus. Channel 2 is low current clamp. 20A scale is 100mv/A. I have Verus on 2V scale. 2v is 20amp on the Verus. I have a fuse)s) out with current loop for coil and injector feeds. Channel 3 is aes wave secondary ignition pickup. 1000:1 attenuation. I have tried a couple different scales. I get different measurements depending on the probe I choose. Trying to make sense of that. The ignition events dont look the way I expected either. Unless I use a aes wave COP Paddle Probe, then the waveforms look more like ignition events, but the measurements are different there also. The current readings change depending what probe I select. Just looking for some clarity. Appreciate any thoughts
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2 years 1 week ago #55059 by Noah
Some ignition coils are easier to get a secondary pattern from than others.
There's scenarios where is just not a viable test
I use a homemade probe on my Verus and I'm pretty sure I've got captures that look very similar to the ones you've posted.
You can try resting the probe on the side of the coil instead of the top, sometimes you need to find the sweet spot to get a usable pattern.
You mentioned 1000:1 attenuation. You don't need an attenuator with the the Verus, you won't hurt it. Especially not with something like a secondary probe, it's not directly measuring spark kV.

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2 years 1 week ago #55068 by Joshasta
my ignition probes come with 1000:1 attenuation. I'm trying to figure out why my voltage peaks change in voltage depending on what measurement scale and probe I choose. I'm not sure what is reading the correct value. Some KV readings seem awfully high especially for a vehicle at idle. and my COP Paddle probe gives the lowest kv readings. Also my amp clamp gives different reading depending if I am using the amp probe on 20 amp scale or using dc probe and 2v scale. Weird thing is I tested my amp clamp and switching back and forth between 20 amp and 2v while measuring current through a light bulb. the measurements were accurate either way. but when I go to my truck, I'm reading different amperage on the same things just by changing the scale and probe selection. any ideas what I am doing wrong?

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2 years 1 week ago - 2 years 1 week ago #55074 by juergen.scholl
The ignition pick up you´re using is just that... a pick up that´s capable of showing you that an event is taking place, not more not less. It is NOT a secondary probe, these are dedicated ones.

The time you put on the capture with the paddle is way too much for the SO scope to give you detail, it will work the other way around: set the timebase to 20ms per screen and later you can zoom out if you want repetition.

The attenuation of the SO scopes secondary probes is 1:5000, different from othere makes and important for proper scaling, hth.

An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
Last edit: 2 years 1 week ago by juergen.scholl.
The following user(s) said Thank You: Noah

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2 years 1 week ago - 2 years 1 week ago #55094 by Joshasta
I was reffering to changing the probe on the snap on verus labscope screen. Cant I switch between KV and Volts DC and still have an accurate reading? The probe I select, and even the scale, seems to give me different measurements. Or maybe I am supposed to only use a 0-10V scale with the capacitive pick ups I have? that seems to give the most likely readings. Is the KV ignition probe only for a inductive pickup?
Last edit: 2 years 1 week ago by Joshasta.

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2 years 1 week ago #55099 by juergen.scholl
What is the part#of your probe? If it's not a SO one could you post a picture of it?

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2 years 1 week ago #55104 by Joshasta
Finally got some better waveforms. 20ms time base was key. Thanks! I have included pictures of my pickups and some screenshots. I am getting 16kv at idle using my aes wave secondary pickup 01-12 regardless of what scale I am using. So I am getting different results today. Not sure why. I saw 25kv the other day. Today I consistently get 16kv if I measure in KV or volts dc since my pickup has 1000:1 attenuation. So that is making sense now. My COP Paddle (Aes wave 01-16) is giving me discrepancies though. I am measuring 16kv with it using the ignition probe setting. and I am measuring 5kv with it using the DC probe and 10v scale. My COP Paddle pickup also has 1000:1 attenuation, so I would expect to be able to measure in volts dc also and get the same measurement. And I think I figured out my amp clamp problem. My 9v battery was dying. and I was wondering why sometimes I had a good reading, and other times I wasn't.

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2 years 1 week ago #55133 by Andy.MacFadyen
Secondary reading with a paddle probe can be inconsistent when used on COPS a couple of years back we wave form from had a Jag XJ owner who had replaced some of the coils to cure a misfire. The misfire was fixed but the secondary from the aftermarket coils were completely different from the known good OEM coils even when switched between banks.

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