For years, my '95 has run fine on 89 octane fuel, with only occasional pinging in very hot weather.. Recently it stared pinging excessively, so I switched to 91 fuel. It still pings, so I ran a double dose of Techron thru the latest tank, but no real improvement.

The pinging seems to happen between 2000 and 2500 rpm, under medium load, and are somewhat ambient temperature sensitive. Freeway rpms are 3K, so no issues there.

I didn't think this car had knock sensors because of the hot weather pinging, but after a search, I read that it does. Also read that they rarely fail.

Has anyone experienced this, and what did you find to be the cause?

TIA

Pete
1995 E-34 124K miles
1997 Carrera S