Had a misfire problem with ye olde Audisaurus now in her 20th year
2 Litre straight inline 4 cyl.Starts OK in the morn but pronounced misfire and after around 15 mins would suddenly cure itself seemingly when it got warm.
Seemed like a switch being closed, missing then suddenly fine firing OK stays that way till gets to be cold again then same thing.
Very odd to me reason why, anyone like to speculate;?...
Assuming it is a petrol: Air leak on manifold can give those symptoms as can a dodgy plug lead which warms and dries and then stops leaking its spark to earth, same for plugs that are tracking down the porcelain. dody distributor cap (if fitted)
Well done that man! Intermittent plug lead, but not as far as could be ascertained leaking to earth anywhere, seemingly open circuit but I'd have though the high voltages would have jumped any gaps but why did it sort of switch On as it were?...
IIRC A hot plug needs less voltage to jump its spark gap, so maybe while cold the spark leaks out the side of the lead, while warmed up the plug needs less and so can be fired, and/or the hot lead is less conductive, either way, once a spark has travelled a few times in the wrong direction it lays a sort of burn track which is then easier to be followed in the future
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