detonation

[atcq110]

I have a stock s13 setup in a 92 convertible 240sx. I got some bad gas in it a while ago and it has been detonating ever since. I have tryed everything to fix it: Plugs, filters, fuel additives. Any one have simmilar problems with there cars?
Thanks Pat

[Dousan_PG]

check your car's timing.