The coil fires and sometimes it dont
what year, car , what size engine.?????????????
on newer cars there are 4 or 6 COP coils.
no year, no joy,,,
sorry, but they evolved each year, so ???
if all coils fail to fire each TDC, that means the
CMP and or CKP are bad.
if you told year, id say.
96+ scan tool it, see the errors, 340,355 etc telling you what sender is bad, as you crake
if older car use the jumper to do same, and get DTC code.
the ECU will in fact tell YOu any time they fail. after 5 seconds of cranking, sure will.
even 1 fail in 10 , causes a DTC to trip.