Try a bottle of Gumout REGANE,
and go back to 87 or 89 octane.
Techtron cleans injectors.
REGANE Cleans injectors, top cylinder, and valves, which removes more carbon than Techtron does.
Here is info on both products...
Techron Additive Penzoil Gumout REGANE (pdf) If the ping is still there it isn't the fuel.
It could be your knock sensor giving an inaccurate reading.
