I got stuck the other day
in a torrential downpour, with my ’99
Ram 1500, 5.2L, 140K. It turned out to be a
bad ignition coil. Is there any way to predict
failure of electrical parts like this, or any recommended
pre-emptive change schedule?
Generally, no, it is just the luck of the
draw. However, in the case of the open-fame,
E-core ignition coils, there is one predictor.
Unlike earlier coils, which were oil-filled and
impervious to corrosion, the later design
the laminations rust and begin to spread apart, the time is near.
used an epoxy-clad coil assembly, with an
open laminated sheet-steel core. The steel
rusts, and, as you know, if you’ve ever tried
to remove a really rusty bolt, steel expands as
it goes back to its natural state—iron oxide.
Just as water freezing in a bottle will crack it
from expansion, so will the expanding (oxidizing
iron) core crack the epoxy. Then failure is
imminent. So, the bottom line: More than a
little surface rust: time for a new coil.
The other items than can leave you cold:
The crankshaft position sensor and the MAP
sensor. If you’re venturing far from home,
toss a spare pair into the glove box.