Ivan, thank you so much for dropping by! I watch your videos all the time, you're an outstanding technician. Dave

Agree Ivan!

It is indeed very good! To think that we used these methods with anologue scopes in the 70s and yet today - and since the arrival of 'serial killer' scan tools - we've all but lost interest in the fundamentals, which can't be seen with a scan tool, as it can with a decent scope!

Agree!

Thanks, man!

What a kind remark, Matt. Thank you! I'm doing a part II, but midway through my brake hydraulics blew out. So, my attention has been temporarily diverted.

Thanks, man. I've sub'd you back, you've got an interesting channel.

Oh Will, thanks for stopping by! As you know I watch your channel regularly, it's an excellent resource. I'm so humbled to get a visit from another one of my favorite KZfaq authors.

Thanks, man, it was a fun video to make.

No problem man ~ I could tell this video was flowing with good momentum and fun to make ~ Look forward to seeing more of your vids in the future...

Thanks, that's what I was looking for. No such thing as a dumb question, if it sounds difficult, it shouldn't be, and it's on me to better explain it.

Thanks, I'm glad it helped!

Thanks for the vote of encouragement, I have more planned but it will likely be a few months.

Thanks for the feedback, I'm glad it helped.

Thanks, you obviously have experience with this topic already. As you know there are a few very long professional seminars posted on KZfaq, and I was hoping to compress that information but also make it easier to watch. I just wish I could have made viewing more fun. Learning definitions can be tedious for those who are seeing this for the first time.

Thanks, man! Dave

Thanks. I'm sorry it was so complex, I really did work hard to make it as straight forward as I could. This video compresses hours of educational information for professional technicians into 17 minutes, and understandably it can be a little dense when you see it for the first time. I promise this will be the hardest video I post, and I hope I can make videos to come more entertaining now that fundamentals are covered. I appreciate you sticking with it and following along, I hope to make your effort worthwhile.

Thanks, it was a lot of effort to make and I appreciate the feedback.

Yes I plan to do more, some time in the next few months. As you say, those last two were tricky. It turned out that if you order the situations according to secondary gap distance, then order the results in terms of firing voltage, the observed results line up with expectation. Same thing if you order in terms of burn time, with the longest gap having the shortest burn time. It was revealing to see those findings on the Ram, although I was a little surprised a shorted wire wasn't more abnormal. I was also surprised how snap throttle revealed the lean cylinder when at straight idle the findings were much more subtle. It's a good reminder that when doing ignition testing it is always wise to record a few sheets of snap throttle to uncover concealed problems.

spelunkerd yes the Snap throttle test is super important to reveal the bad ones. I did some primary test on a mini and in a Chrysler, the Snap throttle was the answer. I put those vids on my channel if you want to see them. Any comments from you would be great. I like to learn as much as I can. Thx again for all your great information.

Thanks, man.

Thanks!

Dang, I was hoping to leave your excellent answer in place for others to read, I see you took it off. Evidently some who came by found this too difficult and complicated, I didn't mean for that to happen.

After I made the post Dave, I thought about how it would be more convenient for others to learn more about the ignition analysis through a discussion of asking questions if they didn't understand. I posted the answers without giving any thought for the newcomers and also to have some more activity on this video. And for those who did find it confusing would hopefully ask questions so they could learn. Sorry Dave in the deletion of the posting and hope you understand... :))

I believe there may be frustration by some viewers about the complexity of my explanations. I didn't mean for this to be too complicated, and for those just looking for answers I don't want to stand in their way. As you know, the short answer is as simple as estimating the gap and then recognizing the relationship to firing voltage. Then pattern recognition kicks in with the lean situation. Cheers, thanks for your input.

I thought you did a great job Dave and didn't see where there was complexity in what you explained. Looking through the posts, I didn't see where folks had mentioned anything about the complexity and all liked the video and thought it was very informative. I always say that when someone whats to know more about a topic that they don't understand, they will ask questions. Again from my point of view, you did a great job with the video and look forward to many more from you :)

What I like most about the Pico is the way their engineers seem to understand the automotive needs very clearly. Peripheral devices like their current clamps and hardware are the critical difference compared to my generic digital oscilloscope, even though technical specs for the scope itself are similar. I had quite a bit of trouble getting a stable reading from a standard digital oscilloscope on a running vehicle. Thank you, for your kind feedback.

Hi Spelunkerd. Thanks for your comment. I wrote an extended reply, which I then started to edit before seeing it disappear. At least, I can't find it, for now :( if it turns up please let me know as I was in the middle of editing, so the beginning makes no sense at all!! Keep up the good work.

I found it on the other video, ha ha. Thanks for watching, I plan to do more.

Is it gobbledygook, because I was amending it when it disappeared !! If so you can scrap it, or I'll amend it, but I can't see it! Glad you plan to do more. (I'm trying to find the time, but I don't have your superb presentation skills and mine would need to be in French. Although I read write and speak French, it isn't my mother tongue and my accent isn't perfect.) You make your videos come alive with just the right balance of theory and practical to make the videos engaging and informative. Spot on: I like your style and admire your skills.

What a kind remark, thank you.

It's so challenging to teach to a group that you don't know, everybody is at a different level. I'm pretty sure this was too complicated for some, and maybe a little too simple for people who work in the field. I appreciate visits from experienced techs like yourself and Ivan, who see these waveforms all the time. These explanations make a lot more sense when you're heard some of it before. As you know I watch your channel all the time, it's great to see waveforms on multiple devices.

spelunkerd it's my privilege to have you on my channel sir. For me KZfaq is the best way to share knowledge and experience. Looking forward for part two. Thank you.

Thanks, man!

Thanks, man.

+spelunkerd second time watching it 😀😀 im into this thing now but is strange how the experts have dissagreements over some points on the analysis...

+spelunkerd A is number 3 B is number 2 C is number 1 D is number 4 Hoping to be right 😀😀

Good for you to go through the effort, thanks for taking the time. As you saw, pattern recognition of the sweeping upslope from a lean cylinder at snap throttle led you to the correct diagnosis of *B=2*. The remaining three can be put into order of how big the gap is. The biggest gap is the open plug wire, next biggest at 0.1mm plug gap, and least biggest with a short to ground. Because firing voltage is determined by how far that spark needs to jump, you should be able to put them in order as to which system will have the biggest gap, and then make a second column of how big the firing voltage actually was in each example. A disconnected plug wire has the biggest gap to jump, so it should have the biggest firing voltage (by far), *A=3*, as you say. The next two are tricky, and honestly I would have trouble telling the two apart in a real world situation. But following through with our logical progression, the next biggest gap is the plug with 0.1mm gap, and the next biggest observed firing voltage is D, so that would suggest *D=1*. Finally, the wire that is shorted to ground (no gap at wire, but still some gap at the distributor) should have the smallest firing voltage, which leads to *C=4*. You can also order these by looking at burn time, recognizing that a long burn time suggests a small gap, which again leads to the same result. Notice how the burn time on C is slightly longer than the burn time of D, because there is no extra gap to jump so all the energy can go into making a long burn line. I think anybody who gets as far as you did deserves full marks on this one. Some guys like to visualize a piece of rope, which they lay down following the curve from the top of the firing voltage to the plateau of the burn line. If a lot of voltage is used up to jump the gap, there is less rope remaining to give a long burn time. Nice to meet you!

+spelunkerd yep i had trouble with those two also 😀 thank you very much because i liked it a lot!

If you like this, check out the channel ThePracticalMechanic. He's doing a free course now through Facebook and KZfaq, looking at various ways to use a scope in different vehicles. He covers COP ignition, injectors, CKP/CMP waveforms, etc in greater detail. On the Facebook page, people following along are posting their traces, which offers the advantage of volume as well. Thanks for watching my humble effort!

Thanks, Richard! Dave

Hey man, thanks for scrolling through my video set! I do that with some authors, too, and it is nice to see others do it on my humble channel. I've been meaning to do another with the COP system, and a few clips are taken. Just side tracked at the moment by other more pressing repairs. Cheers. Dave

spelunkerd i can appreciate the perspective you easily express in your videos. Your comments too, I watch a ton of automotive videos, and sure enough, I scroll down a bit to find you lend some of your knowledge to the rest of us. Thanks for sharing Dave!

Sounds great, I'll stop by when I have a bit of time. I've always wondered how those magneto systems look on a scope.

The main difference is the primary pattern outside of the spark period, like CDI and HEI and so forth it has its own signature. But the spark part is much the same, albeit inverted, a feature my old CRO scope doesn't have. A Pico would be handy with freeze and replay, eyeing them off for a few purposes which is how i ended up here actually. Cheers.

Shane, thanks for stopping by! As you know I watch your motorcycle tech channel regularly. Your situation, where you teach new techs professionally and also reach out to the KZfaq community is a teaching model. One day I'll put my Vulcan onto the PICO to look at waveforms. New bikes coming out these days seem to be loaded with electronics.

Ya, me too, I need the challenge when learning this kind of thing. For some reason people who reply with answers tend to delete their own remarks after the discussion, which surprised me a little. I wish some had left them in place, those remarks were very thoughtful and mostly correct. The lean cylinder is easy enough to identify just based on the shape of the last part of the firing line. Then if you align the remaining answers in order of "biggest gap" electrons have to jump, it will match perfectly with a list of measured firing voltage. Thank you for watching!

@@spelunkerd strange. they maybe doubt they are correct after seeing other comments and retract their own comment due to feeling silly if indeed they were incorrect. getting it wrong is OK as long as you discover the correct answer and in turn understand where one went wrong in their thinking.

In this classic old system, there is only one coil on the vehicle. It makes comparison much less complicated since there is no variance you can blame on probe placement, etc. That coil fires four times for every revolution of the crankshaft, completing a full cycle after two crank revolutions. The distributor sends the spark to the appropriate cylinder just as it reaches TDC of its compression stroke. I wish coil on plug ignition systems were so easy to interpret.

I wish I got a higher magnification shot of the plug on that cylinder, it ended up being just the plug. At 16:31 if you look really closely right at the tip of the probe I'm holding, you can see there is a metal bur on one of the ground contacts, almost bridging the gap. I don't know if that was the cause but in any case swapping out the plug was all that was needed. I don't even know if it was a manufacturing defect or carbon, it looked like it might have been that way right from the factory. If the spark jumped across at the defect, the gap would have been really small, almost nonexistent, but if the spark jumped to other leads you'd get a normal pattern. With a strange jump pattern, I can imagine how a lot of hash of the spark line might be seen, even intermittently. Some guys described a similar pattern when the ceramic of the plug is broken, which wasn't apparent when I examined the plug. One of the humbling things about using this tool is the broad variance in what you see practically. So, I try to avoid overthinking problems, often the solution is unusual variance in a common problem, rather than something more rare. Thanks for watching!

@@spelunkerd Thanks for the final diagnosis, very interesting indeed. One thing I've learned over the years is to first determine if the spark is internal or external when examining ignition stuff, awesome work!

Good questions! If you follow ScannerDanner here on KZfaq, he goes through the details of how to do that in several videos. Coil on plug ignitions are tricky, since they don't always provide access to the leads you need to view, and since you can't nicely line up waveforms on a screen. Even the ground side of the primary circuit of most COP ignitions is impossible to tap into. Some ignitions permit the use of a secondary extension wire, which is just a short length of spark plug wire you add in series to the coil so you can put your capacitive pickup on that. You might destroy evidence with that if you've got a short from boot of the coil to adjacent ground. One way around that is to measure primary current ramps by tapping into the fuse supplying the coils, but some vehicles like my GM use two different fuses so you need to do one bank at a time. Also beware the chance of other devices on that fuse. Another option is to use an inductive 'paddle' pickup lead which is variably effective depending on the shielding of the coil. In the Pico4425 kit they supply a paddle, so you can use that one to see secondary ignition waveforms, one at a time. It is really fast but the wave shape changes depending on how you orient the paddle, so interpretation is limited to gross abnormalities. PineHollow Autodiagnostics posted an excellent case study this week of a misfire under load, using that very technique.

I've been meaning to to another video of COP vehicles, and some clips are done. As you say, if you look at one bank at a time like I do on my Chev Suburban using primary current, you get uneven spacing. That's because the firing order swaps sides, the gaps are when the other side is firing, a normal finding. If you print out both sides and lay them on top of each other they fit perfectly, filling the gaps from the other side. With a little detective work you can identify which cylinder is which by looking at the firing order and noticing the unique cadence of where the gaps are. It should be enough to infer order without having to use a channel to flag one cylinder. Alternatively it's easy to add a timing channel. As you've noticed it is easy to get current ramps for each side, although I like the palisade of waveforms with the old system. There are so many variables with a cop system it is harder to interpret waveforms, but gross abnormalities stand out. Thanks for watching, and for adding a thoughtful remark.

Wow !!...It just occurred to me that the firing order alternately fires each cylinder...DUH !!...I removed a fuse (injector) which feeds not only a bank of cylinders for ignition but also the injectors...wasn't sure if you could get an accurate waveform with both the ignition and injectors getting fed from the same fuse...I picked the ground wire for each bank being that there is a harness connector on each bank on top of the engine and it was easier to clamp the amp clamp around that ground wire...the Corvette has a separate coil for each cylinder. I'll do what you said about laying both waveforms on top of each other...my next waveform is getting my cam/crank...haven't done that one yet but I'll have to get the 2 signals from the PCM which sits inside the front L/H quarter panel...much easier than trying to get to the cam and crank sensors on the engine...THANK AGAIN and I love that Picoscope !!

Yes, my 2000 Suburban is the same, primary amp clamp on that middle connector on each side. I've also done cam/crank. It was easier to identify the wires at the PCM, but if you do that remember you don't necessarily need to undo the bolt holding the connector onto the PCM. You just need to carefully pry the plastic guard off the back, then identify the wires. I punctured the two wires and repaired the punctures with liquid tape. I also labeled the wires with little tags so I can get to them easier in the future. The wire coloring for mine was at variance with the diagram, but the connector pin number was correct so if you need to disassemble to get pin numbers then you need to do that extra step.

Suburban, Corvette...same thing...both GM...LOL !!...I'll puncture the wires also and use my liquid tape when I'm done...I'll check those wire colors too but go by my FSM I just bought a few weeks ago...3 BIG volumes !! ...I'm doing all my sensor waveforms with the Picoscope so in the future I'll know what's good...I'll work on my daily driver 4 Runner next...marking the wires sounds like a great idea !!....I've had the PCM disconnected and apart a few months ago to see if I had any corrosion inside on the pins...C5 Corvette's have big problems with this since it sits below the battery...battery acid is not a friend to PCM's...I then sprayed some corrosion inhibitor called Pro-Tec on the pins when I was done...great stuff !!!

I'm glad to have you on board, I hope to post more over the coming months. Cheers!

Not needed for those capacitive pickups.

@@spelunkerd thanks!

This is a really good question in general. You need an attenuator when directly measuring voltage in secondary ignition, but this style of capacitive pickup lead is internally protected so you're safe without. You also need it when measuring voltage directly on the switch side of the primary wires for vehicles with two-wire ignition leads (like this one). You do not need it when measuring current with an inductive device, like I did in the video. Interestingly, with three-wire coil-on-plug ignition wires, the ground switch side of the primary is contained within the electronics of the coil, so you unfortunately can't get to it! So, for a COP ignition fed by three wires you are pretty safe, but you won't be able to find the pattern you want to see. For those vehicles, some guys use an extender secondary plug wire to give room to attach a capacitive pickup lead. Others use an inductive paddle to try and pick up the signal, where you don't need attenuation, but the signal is variably shielded and not easy to interpret. The other common place to have dangerous overvoltage is on the ground switch side of fuel injectors, where you can get a scope-destroying overvoltage spike between the switch and the solenoid. Interestingly, for other solenoids like evap solenoids, usually the spike as the ground is switched off is not so dangerously high, presumably because the coils are smaller or because they incorporate a flyback diode to flatten the inductive spike. Even so, to be cautious I'd consider an attenuator for big solenoids until you can verify that the inductive spike when switch turns off is not so high. I hope that helps!

@@spelunkerd Thank you so much for this reply. this is very helpful as I am trying to learn how to use my scope more effectively. I saw online where someone had made a lasso with a piece of wire to go down into the spark plug well on the end of the coil, and then the middle of the wire had a bolt to connect the inductive clip, then finally the other end of the wire was an alligator clip for grounding. I'm considering making one of those. If I do, would I still be safe to clip my inductive clip to that bare bolt in the middle? Or should I consider putting electric tape around it so there's no metal to metal contact?

@@Z14kt12timandjes1 Gee, I don't think it needs to be so complicated, and I wonder about the safety of DIY uninsulated wires carrying such high voltages. For COP vehicles I'd use an extra spark plug wire as an extender, then clamp the capacitive probe around that.

Excellent question. No need for attenuators with these inductive and capacitive pickup probes, only needed when your scope is tapped into the circuit measuring voltage.

spelunkerd thanks for the reply. Funny I figured that out the day after I posted my question. Excellent video. Thanks for posting.

I'm not sure which waveform you're referring to, but the greatest challenge will always be sorting normal variance from pathology. You could leave a video time stamp if you want to discuss it further. The EGR system in this vehicle is fine, and I suspect EGR problems may be hard to find on a scope of secondary ignition. These old style ignition systems were so much easier to study because everything runs off the same coil, making some problems glaringly obvious when you have a palisade of ignition spikes to compare.

time stamp 16:03. Egr might effect multiple cylinders but some type of turbulence.

@@spelunkerdcheck out this video at time 26:09 kzfaq.info/get/bejne/fd2mibimlc3Ll3U.html

@@simclardy1 Yeah, that's a good reference, I have always liked his clear presentation style. In this example the problem was solved by replacing the plug. I didn't get a very good shot of the plug on this video, but there was a defect in the plug tip that I think happened at the factory. It would have been interesting to see whether grinding that nubbin of carbon off the electrode tip would work, instead I simply put in another one. Since it affected only one cylinder I didn't even consider EGR problems. Thanks for stopping by!

@@spelunkerd thanks that is helpful. it also keeps the rule of dividing the burn line and left of line points outside. in the example I gave the turbulence clearly starts to the right. cheers

Yes, I have seen it, also worth watching. For those interested, the series by the channel "Dead on Diagnostics" is excellent, too. And of course "Scanner Danner" always has excellent content, with a real time diagnostic plan that is brilliant and practical. Speaking of practical, South Main Auto and Pine Hollow Auto Diagnostics are both brilliant examples of real time diagnostics in the field. What an age we live in, KZfaq is a constantly rising bar.

Yes it is...just found D.O.D recently....excellent material !!...Danner, Matt, PHAD, and SMA on my fav's list ...haven't found any better...these 4 guys are LEGENDS !!!