I always run 87 octane, even in states where "regular" unleaded is 85 octane. Again, this was a new thing that had never happened before. The "usual" pinging could happen at any elevation or temperature and it ALWAYS went away with a reduction and reapplication of the throttle. It was completely random. I could go for months without it happening.
The pinging issue I just experienced was on the last day of a three week, 4,000 mile trip. I hadn't experienced any pinging incidents the whole time. I have serious doubts that it had anything to do with that particular tank of fuel since it went away and suddenly as it appeared. Same elevation range and temperatures. I drove another three hours and had to go up more long steep grades with not a hint of a problem.
With no codes being thrown it's possible the knock sensor has failed. Unfortunately, I hear it's a major pain to replace.
