That brings to mind many years ago shorting a plug to earth with a long screwdriver without noticing that the steel shaft went right through the wooden handle. I should have made contact with the cylinder head first.
Thanks. Havn't needed to do that test for a number of years. I think the coil end was completely inaccessible. The other way to spot a non-firing cylinder is from the temperature of the plug. Point about voltages is well taken.
on old engines plug insulation was accessible and feel/measureable, but not now and by the time you get the plug out, unless it is soaking it is hard to tell from temp.
I had a the earth lead fall off a motorcycle engine. I found out that the alternate ignition earth path was though the clutch cable, HAND LEVER, handlebars, top yoke, headstock bearings. I did rest of trip doing clutchless changes up and down except for pulling off from the few stops.
Nearly as exciting was my A35 van, the starter was operated by a pull handle on the dash, the engine earth lead failed and the return path was through the starter knob wire, much excitement ensued as the cable welded itself in the pulled position and the starter continued to run while the cable smouldered. I pulled the battery connector off, as in those days they were a lead cone just pushed onto the battery, you were meant to put a self tapper in to hold it firm, but no-one did, good safety feature in my case.
The engine earth lead (partially) fell off my Rover SD1 and when I started it (on a shopping trip to Cambridge), the current flowed through the throttle cable, welding it solid. After much "waggling" I managed to free it off so it had 2 positions - full throttle and idle. Driving it home from Cambridge was ... interesting. ROAR - coast - ROAR - coast - ROAR - coast
when the same thing happened on an escort van we got a piece of wire and used it as a pull throttle through the window!
I've got a lovely back street garage I use. Father and son outfit - son is brilliant at electrical problems and diagnostics (and a fair mechanic), dad is proper old school mechanic, listen to a car to know what's wrong.
Wouldn't go anywhere else.
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