Sir new development palang po. kakapa change oil, change filter ko pa nga lang sa petron I think 700km palang natatakbo after the procedure ng vios sa petron.
my wild guess would be, your engine is pre-igniting. check ignition timing, po, and adjust if needed.
my other thought is, you need higher octane fuel, or better fuel quality.
btw, how's your fuel filter?
How about 97 LXi?
Civic horsepower