My '97 TBird 4.6L has been with me for about 2 1/2 years, now, and was knocking and pinging horribly for about the last year / 12,000 miles. It only has about 45,000 miles on it as of this morning, and the original owner from whom I bought it was the stereotypical Little Old Lady who only put about 20,000 miles on it the first 7 years of its life, so it was pretty much mechanically a cream puff when I got it, with just scratches on the body as evidence of its true age. I read and tried / checked all the things I could find here and on Crown Vic and Grand Marquis forums (I also own a 2005 Crown Vic Sport) about knocking and pinging and how to fix them, but all's I could figure as a fix was to run 93 octane. I tried absolutely everything else. Finally, about 10 days ago, the CEL came on, the car threw me a code, and it said the bank 2 O2 sensor was bad. I was on my way home from work, near home and nearer to an AutoZone when the light came on and so I stopped, they read the code, and I bought the sensor. The OK mechanic (not as good as I am, but he has lifts and more tools) I sometimes use was only another mile away, so I rushed over to his shop to see if he could install it for me before closing, but it was already too late and he was backed up, so I had to leave it. I told him how often you all say the code is frequently bogus and asked that before installing the sensor the next day, he instead first do what he could to more thoroughly diagnose it and only then do whatever he thought was needed to cure the real problem. Long story short -- when I called him around 4 the next day to see if the car was done, he told me he was just about ready to start working on it. When I got there at 5:15, his helper told me he (the helper) had simply changed the sensor, that the boss had done nothing else. I was pissed, but hoped the $60 some - odd Bosch sensor from AZ and $25 labor would just possibly fix my problem.
Well, today, after nearly 500 miles and the last couple of hundred run on almost straight 87 octane (had to burn off the 1/2 tank of 93 I started with when the job was done), there is absolutely NO knock or ping anymore, and the CEL has not come back on -- seems like this time, it really and truly was simply the code that was thrown was correct!
Now, why the hey did the sensor go bad in less than about 30,000 miles? Does age play a role and not just mileage / hours of engine operation? It was fine when I got it, but it had been just sitting in the original owner's yard for nearly 3 years.... I wonder why the other one seems to be still good, or how long before it too will bite the dust??? Very strange, but now I can burn the cheap stuff again without fear of doing serious damage! Car runs GREAT on 86 octane!!!
(I have no idea how those little squares got in here -- I cut & pasted this from an EMail I did at work and sent to my home so I could post it when I got here?!?!? Sorry!!)