Is this the underlying problem or a symptom of something else?
I have a 1999 Ford Expedition that has a knocking and pinging problem. Two different mechanics have narrowed it down to the ignition cable (spark plug wire), but I have replaced the cable three times now over four years and I need to do it again. The replacement normally works for a few months to a year or so depending on the quality of the cable, but then slowly the knocking comes back and gets worse. It also in the early stages only happens on up hill grades and in higher gears, over time the problem becomes more constant but always above the 2nd gear. The vehicle is an automatic. I also have a very slow oil leak I have not fixed on the engine. I mention them in case they help pin point something.
Does anyone have an idea regarding what the root cause of this might be?