2005 Dodge 3.8 misfire. Waveform question

I have a 2005 Dodge Grand Caravan 3.8L with a random #4 cylinder misfire. I have attached a photo of a screenshot using my Snap on modis scope with the inductive pickup on cylinder 4 plug wire attached next to the coil pack. I circled the waveform in question which I could not find any examples on line or while looking through Paul’s book or premium channel. Has anyone seen this waveform and what does it indicates? I am a diy mechanic and greatly appreciate this channel and Paul’s time and energy teaching others skills he has learned. I keep the 2005 caravan mainly as a trainer for me to learn these skills. Any help would be appreciated. Additional information is my short term fuel trim is less than 5 and long term is negative 32. I am embarrassed to say I have changed upstream O2. Fuel injectors ( never changed fuel injectors before so wanted see how difficult it was and it was not.) Fuel pressure is 58 psi ( that is specification). Not sure why van is running rich. Any help is greatly appreciated!

Has anyone seen this waveform and what does it indicates?

It's a bit difficult to say at this zoom level. If possible, could you retake the waveform with a higher voltage scale? And zoomed in closer to the #4 firing event? I can't tell if you've got Peak Detect on or not. Keep it on if so, turn it on if not.

For our info, is #4 misfiring? If so, you might consider looking at a known good cylinder while you're looking at #4 again.

There is extremely high kV demand (independently from scaling when compared to the other events) and no spark.......this for sure looks like an open in the secondary, possibly wire or plug or even the coil.

Tyler wrote:

Has anyone seen this waveform and what does it indicates?

It's a bit difficult to say at this zoom level. If possible, could you retake the waveform with a higher voltage scale? And zoomed in closer to the #4 firing event?.

I think the trace shows #4 firing events only. Looking closely at the image one may see that every other event requires a higher firing kV. I take this as the cylinder firing under compression and the lower ones as the waste spark events. Between each coil firing you possibly may identify two more events/interferences which would stem from the other coils/cylinders firing.

Sure a lot of "supposing" but if the capture was taken at idle the visible time in the picture corresponds to roughly a second. I totally agree with Tyler that different configurations while capturing the data will result in more and better information. Using the screenshot function of the modis allows better images and hence easier analysis.

Thanks to all who have responded. After reading your replies and further research I agree this high firing voltage is due to high resistance or bad plug wires. Plug wires are only a year old and I thought should be good but after watching more of Paul’s videos i realize plug wires may not last long. I have attached another image with voltage scale and time visible. My main question is when I see a high firing voltage With a sliding board style spark line does that indicate no flame in the cylinder? Since the spark line is not horizontal it doesn’t seem like the fuel ionized and the spark jumped. Since this event displays one high resistant and the next low is the low firing line the waste spark? Thanks again for all your help. It’s nice to know others are willing to help. God bless you guys.

Please could you change the scope settings and then repeat the capture. I'd want you to turn OFF the filter and to turn ON peak detect.

The kV scale does NOT show extreme high firing voltage although there is no spark in the combustion chamber happening. The kV demand of the waste spark rules out an open plug wire. Could you upload the LSM fi!e?

Agree with Juergen about the scope settings. We need to see some detail on the #4 firing event.

If you want, you can get the .LSM file off your Modis Edge and email it to me at wrenchturnsyou@gmail.com. That'll make viewing the waveform much easier. ;)

Also, is the #4 cylinder misfiring?