"...i hear a small rattling sound every time i push the gas pedal down. I hear it coming from the engine bay area. it loud enough for me 2 hear. This happened a while ago and i ignored it but now it keep happening and is really annoying."
It could be a number of things like people have already mentioned. We had the same problem on both our Sentra's. We have no A/C so I'm not sure if my probable cause will be valid.
Has the sound gradually become louder over the past few months with more than casual driving? If not I guess you can stop reading. If so, your problem could be caused by faulty plastic sprocket guide spacers. This noise will be noticeable on the left side of the engine behind the sprocket cover. It may sound like it's lower in the engine or near the middle while you are in the car which is deceiving. You will hear a ticking/rattling noise that will ocassionally happen. Over a few months the noise will get worse and becomes more apparent when the engine is hot. Some days it may not act up at all untill the guides fall apart This is an apparent problem with pre 94 GA16DE engines (95 model for me in Canada). The plastic guides eventually wear and break (for us on both cars, around 110,000 miles or 185,000 Km's). When this happens the camsaft and crankshaft will be out of sync possibly causing damage to the cylinders. If left unfixed the timing chain, which is now slack, will eventually wear a hole in the sprocket cover causing extensive damage and oil leak.
For us it cost $1400 CDN to fix since the chain did make a hole in the engine. My father's theory of maintaining a car, don't fix it till it breaks. If this problem was caught earlier it would have been $750 CDN to repair. A few months later and the same problem appeared on my B13 Sentra although with higher mileage (197,000 Km's). Once the noise was constant, not happening occasionally, the car was shut off and left in the driveway where it still it. Can't afford to get it fixed right now but it gives me time to paint my calipers. Thankfully we have a second car and a van.
You can purchase timing chain replacement kits from:
http://www.courtesyparts.com/B14_TBKIT16.html
For further information check out this site:
http://autorepair.about.com/library/faqs/bl619a.htm
Happy tuning,
Greg