My 92 XJ has started spark knocking when I've sat in traffic or its hot (85+). I've tuned it up, changed the fuel filter, and it still knocking. Running 94 octane covers the problem but its still there. Has anyone else run into this ? thanks, DB

Your timing is to advanced or you might have a vacuum leak.
A knock at idle is not very common, is it doing it just setting there or when you first get on the gas?

If doing it all the time I would look into the knock sensor.

Grab the codes and see if it is telling you anything there.  You can read the codes for free at autozone or similar, or cycle the ignition switch 3 times and read them flashes of the CEL on the dash.

Andy

Its doing it when the motor is hot (200) and when i'm accelerating. If i run high octane it stops, but starts as soon as I put 87 back in it clatters. My mechanic checked my vacuums just a few minutes ago and said they all looked good.

Andy

Thanks for the info Andy, youve helped me out tons over the last few months.

Andy