Couldn't find anything on this when I searched. My car (1994 525i auto, M50TU) pings on most upshifts. I've seen some discussions on decarbonizing methods, but wonder if retarding the ignition a couple of degrees by moving the CPS pickup has ever been done?

I had a '95 Mustang for a while that pinged a lot. It had an "octane plug" in the engine wiring harness. Pulling the plug retarded timing 2 degrees throughout the operating range. Eliminated the pinging instantly and it ran better, too. I was told by techs that this was done a lot here in Portland because we get low quality gas. Wonder if something similar can be done to the bimmer.

Thanks for any thoughts!