My usual method for this involves pulling plug wires with the engine running (ouch) or feeling the header tubes (OUCH). I wouldn't mind a less painful method. Never had an oscilloscope, good for this? What else can you do with one? What other methods do you use?
I've actually used my old inductive pickup timing light to see if the plug is firing - if it is oil fouled or whatever there won't be a trigger for the strobe.
Get one of those clip on spark checkers. Clips onto a ground point on the engine and the plug wire plugs into it. Cheap at the parts store. That's what I use or a screwdriver stuck into the plug wire and spaced a little off a ground point to watch the spark. If it's the only cylinder not firing it's prob the cap or the wire.
Use an IR thermometer, that's how I used to look for a dead cylinder on the big diesels. Keep in mind from a cold start the end cylinders will be a little cooler.
There used to be a nifty little gizmo which took the place of the spark plug, but was made of glass or ceramic, which would let you see what was happening in the pot while it was running. You could diagnose problems by the colour, etc of what you saw. I think they were called "Colourtune" or similar. But a spark plug shoved into the lead with a big alligator clip on the thread to ground has worked for me for about 100 years.
You could also use a spray bottle with some water to spray the exhaust pipes. If the cylinder is not firing, then the water wont burn off. Brian
Harbor Freight sells an in line spark detector...goes between the plug and the coil... Ya got spark it lights up...pretty inexpensive and easy
A pair of nonconductive pliers like these will take the ouch out of spark plug boot pulling. Not sure where to get them , as I have had these for 30+ years
A fellow over in another car was "troubleshooting" a buddy's mechanical lifter V8 that ran a little rough. They determined one cylinder wasn't firing. Changed the spark plug with a new one. Changed the spark plug wire and installed a new distributor cap. Then Pulled the head and by appearances felt the plug hadn't fired in a while. Later they reported it ran great after correcting that the exhaust valve was adjusted too tight.
Yes, a non-contact thermometer, just checking spark doesn't always tell all about a dead cylinder. Leaking valves, rings, loss of compression also is a cause.
Great ideas guys. I remember trying the inductive timing light test long ago but got mixed results. Does it flash only when the plug fires or will it still flash on a an open or shorted plug?
You can get a similar tool at any place that sells industrial tools, just ask for a fuse puller. They come in different sizes. I've never seen one with the finger holes like this one though. Good Luck
To answer your question, yes an ocilloscope will tell you a damn lot about the things you can't see! Of its worth the money of buying a new, I would say NO! Finding a used one that works, hell yes! It's possible to do a read out of the primary site of the ignition and the secondary side. It can tell you if on cylinder does nothing, if one does to much, if a plug is dead or draws to much volt. If you could find am old diagnostics tester with a scope and a CO meter you would be unstoppable in making an engine e performed it's best. It can do an dynamic cylinder ballance, that's like doing a compression test but letting the test and motor do all the work. It will tell you so many things in a hard beat. It will even tell you if you got a bad valve, low compression or faulted plug.
Yes and no. The question as I read it was about the qualities of a oscilloscope, foremost. Than what else. A compression gauge only tells you witch of the cylinders is down, not why. An leak down test tells you a lot more, in one gentle go. But again that might being me being slow.
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