at one point i had low octane in there but it was only because i had my wife put gas in it and i forgot to say something. but couldnt say for sure if that was what was in there when it happened. but now that you say that,before this happened a couple days probly i did get a code 53 for a split second. is detonation pretty common on running low octane just once. i dont want to take the head off till i get my new hg. the one they sent got creased by ups.