As someone who has been in the field for almost 10 years as a mech/"parts hanger", you are doing a awesome job and are constantly teaching me things I should have learned years ago. Keep up your channel, you are doing awesome work. I guarantee you are helping people like me(who are too scared to admit it). You are a better technician than 70% of "techs" in the field who shotgun parts in lieu of actual diagnoses.

So nice to see a video that shows full learning curve. I bet a lot of other channels would have edited it to show that they "knew" that the bigger spark could be incorrect. Love it , correct way to learn.. raw and unedited. Also gives people confidence to ask further questions even if they think they have found it. Excellent

Ignition coils are easy to diagnose when they fail completely but can be very tricky when they only fail under load or occasionally intermittently under load. Good video tutorial.

I have spent days watching your videos and taking notes during the lock down ; you are a fantastic teacher.

Brother Matt .. Where have u been hiding Ole Chap? Lol ... Good to see that u are still at it great video man thank u for sharing

Had same exact issue on my friends 02 impreza. Even reported the misfire on the incorrect cylinder. Thanks Subaru. 🙃

You have a definite talent to convey information, I followed you every step of the way, even when you shifted direction. This was a very eye opening one - What you see is what you don't get. Nicely verified tho.

we had a Subaru towed in from another shop who couldn't figure out a problem. It was a bad wire but it was weird that it had a dead miss at times and no code at all for the bad cylinder. Eventually a code set but it took nearly catalyst damaging time to do it. I was shocked that it didn't have new plugs and wires on it and to my fault I went straight to compression, assuming they already checked spark! Lesson learned...

Ha ha ha, that's so funny. You're using a tether to avoid losing your wireless device, great idea!

Simply ingenious! Superb diagnosis Sir. God bless you for this and more hopefully coming in.

This video provides valuable supplementary knowledge to the scope training on the paid channel. It also serves as a good reinforcement example for the ignition systems series. Together, these tutorials provide the best auto training on KZread. Simply unbeatable.

Just saw this... I love your "Test don't guess" philosophy. As a retired professional wrench bender, we have a couple of differences. 1) Time is money & 2) experience breeds patterns. Like, Subaru's have a coil issue, so I, as a professional would have zoomed in on a coil test, all man made things have inherent weaknesses. But, that's not what you teach a DIY. So, Good job! And yes, in a waste spark coil system in which a coil is shared by two cylinders, both cylinders will be affected.

thanks for a great vid and walking us down the diagnostic lane of success

One plug fires positive and other negative. This is why you had to invert the firing line to see. Cylinder 3 and 4 fire at the "same time" and are in a series circuit on the secondary side of the coil. Energy leaves one side of the coil and returns on the other side. Windex works better than the test light for finding leaking plug wires as long as not in area of wire which is inside of the head. I have watched a few of your videos, but you really need to change wires also as the coil has a carbon tracking problem some where. Carbon tracking is caused by high voltage burning the carbon out of the air leaving a semiconductor trail. IF this carbon tracking happens to be around the tower it would have transfered material onto your plug wire. Then the plug wire would transfer material back to your new coil causing repeat failure after time until both are changed at the same time. Also worn plugs are going to stress your secondary insulation, and or any fuel delivery, vacuum leaks, valve sealing issuses etc

Excellent job figuring that problem out, it was a thought provoking challenge!

it's always good news when Matt puts up a video on youtube

Third guy to comment! Keep up the good work with the videos! And thanks for the insights on my project, a 2000 Dodge Ram 1500 with no injector pulse that you commented on a couple of months ago. Still not done as this time of year my work hours average 60 to 70 hours a week. The truck is on the back burner for now. But again a huge thank you!!

Your waste spark coil is internally shorted and breaking down under load, as evidenced by your scope on #3 at higher rpm. It might also account for the bank 2 O2 code, since #4 had a weak spark at idle.

Great work again! No necessary parts bought or replaced, but real ace diagnostic.

Great Diag Matt! Gotta love the scope. Awesome troubleshooting strategies and explanations!