Ok, i have searched extensively and i am dying for an answer.

What is the difference between detonation/knock/ping?

Because my car is making this sound, really hard to describe. Its kinda like gurgling type noise on the offbeat of the engine combustion. Its not metallic, its not that loud, but its there and it sounds weird. I tend to think its detonation or ping. Its mostly under load, up hills, pushing lower gears, etc.

Can anyone definitively describe the sound of detonation or ping? even better, does anyone have a sound file of it? I can try to record a sound from my car, but it would be hard.

Any suggestions on further determining this noise?

thanks!