I've owned my 99 Ford Crown Victoria LX since it was new. No one has worked on it except me. It's had the usual problems: cracked plastic manifold, blend-door actuator, 2 alternators, 1 water pump, upper and lower ball joints, window motors and of course those pesky coil-on-plug coils.
It has always had a tendency to ping so I have routeenly mixed high test with regular gas. Recently it has begun to ping badly regardless of the gas octane. I'm in South Florida where its usually hot and humid. The pinging stops completely after a heavy rain or if it turns cold. Not sure if its related to the humidity (lower), air density & temperture (cooler) or even bariatric pressure (low pressure weather system). no codes!
I believe its some faulty sensor causing the car computer to either over advancing the timing or lean the fuel mixture. Funny thing is today, (the next day after it rained) its still running great with no pinging but its not raining, just overcast but it is cooler by 10 degrees or so.
Things I've done:
Mass air regulator (cleaned)
Air filter (replaced)
Fuel filter (replaced 20k miles ago)
High performane COP and plugs (installed 50k miles ago)
update: changed plugs, fuel filter, found some water in fuel filter - added iso heet and filled with high test.
Now the pinging is limited to times when the car has been sitting with the engine running for an extended time (an hour or longer). the rest of the time it runs great with no pinging.
unfortunately at those times it pings a lot. it is not overheating bearly beyond mid guage. I've ordered a thoddle position sensor.
Things I'm thinking about but have not yet tried:
02 sensor (never changed).
Fuel pump, but runs great at highway speeds.
Possible carbon buildup? (has only 133k miles, running no thermostat Florida but temp still within normal range)
Bad computer? (purchased one but not yet installed because its a "pain in the A" to get to)
EGR vacuum leak but no rough idle and the problem is under load.
Thottle position sensor, but shouldn't that also effect its performance. Running great!
Has anyone had experience with this issue ? What else should I try?