pinging with premium + octane boost

[windboater]

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?

[65comet]

I've had pinging from a couple of things. Spark plugs with broken electrodes causing an extremely large spark gap. Cracked ignition module that slowed down the signal to send spark command and thus spark was occurring later than it should have.

[windboater]

Originally Posted by 65comet

I've had pinging from a couple of things. Spark plugs with broken electrodes causing an extremely large spark gap. Cracked ignition module that slowed down the signal to send spark command and thus spark was occurring later than it should have.

Thanks for your input. Wouldn't hurt to pull out a few plugs and check it out. Don't know what I would do regarding diognosing the module except just replacing it. I'll wait on that as it work fine at time. Regards windboater

[65comet]

Best to pull all the plugs. It only was one bad one the last time it happened to me to cause the pinging.
The module was a problem mostly when it rained and got a little moisture inside on one car, and another car when it got hot and expanded. I saw the cracks which is usually the only way those are found to be the problems that I know of. A strong light and a pair of 3.00 magnification reading glasses from the drug store will usually spot them.

[windboater]

Originally Posted by 65comet

Best to pull all the plugs. It only was one bad one the last time it happened to me to cause the pinging.
The module was a problem mostly when it rained and got a little moisture inside on one car, and another car when it got hot and expanded. I saw the cracks which is usually the only way those are found to be the problems that I know of. A strong light and a pair of 3.00 magnification reading glasses from the drug store will usually spot them.

I've changed four today but no bad plug so far and no change in the pinging. Tomorrow the other four plug will arrive. Thanks

[windboater]

Originally Posted by windboater

I've changed four today but no bad plug so far and no change in the pinging. Tomorrow the other four plug will arrive. Thanks

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).
unfortunately at those times it pings a lot. it is not overheating bearly beyond mid guage. the rest of the time it runs great with no pinging. I've ordered a thoddle position sensor.