I have a 1994 Explorer that until recently has run great. On three separate
occasions over the course of the past week, the engine has started "pinging"
for a few seconds followed by a large puff of smoke from the exhaust.
I have changed the plugs and wires, cleaned the MAF and have added fuel
injector cleaner to the tank.
What else could be the culprit? Like I said it's intermittent but when it
happens, it leaves a large cloud of smoke behind. By the way, the vehicle
has 143K miles.
Thanks in advance,