I have a stock 99 civic SE automatic 4 doors and recently I discovered a very stange noise when I'm accelerating and also when I'm trying to climb hills. It sounds like a coffee grinder noise in my engine. When I'm on P and pushing on the gas, the noise is not there, only when I'm using very much of my engine on D. Any idea ?

 

I finally went to the garage, and it was a problem with the timing of my engine. The spark plugand the crank shaft were not on the same timing. A little adjustment and everything is fine now. I'm getting much more performance also and my fuel consumption drops dramatically. So if you're hearing that kind of noise (the easiest way to describe it is like a single coffee bean in a coffee grinder), you must bet on something about the crank shaft and the spark plug.