SOMETIMES when my car is idling in teh drive way my car makes like this ong ong ong ong sound then it cuts off then it comes back randomly. Could this be knocking??? The sound just worries me but it doesnt happen all the time...I heard that sound when i first got the car 3 months ago when i was using like arco gas but i switched to shell and havent heard that sound -4until today.
Oh yea the car never makes that sound when i'm driving and giving the car the slightest amount of gas. The sound is only created if i let the car idle. Sound is fairly distinct. again the sound only occurs rarely. Could it be my heat shield?

 

Little more info on the car would help. Year, model etc. Any mods done to it? How many miles are on it? Manual or Auto? I highly doubt it's your heat sheild, that's a rattling kinda noise that you can't miss. Also no chances are it's not knocking either. If your using the right gas then it shouldn't knock at all.

 

99 prelude base AT 130k miles. Kinda sounds like that sound from the heatshield, but the repitions of the sound is much slower. I use 91 from shell

 

sound seems to be gone now.