Runs Rough

I took it down the block and it started bucking real hard at times…. But even when it wasn’t bucking, it felt rough as if one cylinder was not firing. The bucking was not just a simple misfire from a plug wire breaking down, it was more violent and random than that. Part of The Feel is understanding the subtleties… I don’t know how one can learn this without lots of time in the shop. I certainly will not claim to be Mr. Know-it-all in this area, but I think I’ve learned a few things over the years.

I popped the engine cover off, did a quick visual, and then hooked up the ignition scope. No scanning for DTCs or checking fuel pressure. Why not? The Feel told me not to worry about those things. Maybe later. Wait a minute you say…. Why did you jump for the scanner on the Metro misfire but not on this one? The Feel… Many of you know what I’m talking about. No it isn’t just because it’s another Chevrolet, I’m pretty sure I know what I’m feeling. I can feel what is probably an open plug wire but then ALSO something more sinister. The Feel can and will lead you astray from time to time, but more often than not, it will be a good friend. Allow it to speak to you and consider the source <bg>. Now lets take a look at a scope shot

Simple open plug wire? Looks like it from here. But there is no way that this was causing what I felt. Secondary ignition analysis certainly consists of more than this (to be covered in another study), but for now just trust me that everything else looked good. I replaced the wire and looked one last time before scratching my head.

Hmmm, looks good (as well as the other tests). I was just about to unhook the scope when this happened as I was loading the engine down.

Ok, I think I know what happened…. What would you say the relationship between this Astro and the Corvette Opti-Spark igniton shot below would be?

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