'87 Mercedes 300e Pinging

[stormyc88]

Hello All,

Does anyone out there have any ideas what could cause an 87 300e with m103 to ping when you lay into the throttle? I'm using 93 octane gas (91 is required). I installed the following tune-up parts about 1 year ago: Bosch distributor rotor, Bosch cap, Bosch dust cover, Bosch wire set, and the correct H9DCO non-resistor spark plugs (torqued to the correct 15 ft-lbs), and all of it was ordered from Mercedes using my VIN, so I know it is all correct. Also an air filter from Meyle of Germany. It was pinging before I did the tune-up as well. Could it be that the coil or crank sensor is getting worn out, or maybe the pistons have too much carbon built up?

Any ideas are greatly appreciated!!