While I am driving when I am pressing the gas pedal it makes a scraping noise but not all the time. If I hit the brakes it will stop. I have a 2001 Nissan Sentra GXE

I'd check the brakes and the wheel bearings. Just everything in the suspension on that corner. It could be a number of things, but I definitely wouldn't drive it until you check it out.

This sounds like a CV joint is bad. It is binding up and locking and then slips when you move.

check to see how much pad is on the break pads also remove the rust around the disk as this some times catches on the pads making a scraping noise hope this helps ivan

There are few possibilities that can cause such problem.
I recommend you few help links related to your problem.Click the link below and follow the troubleshooting;-----Idles rough and quits when gas pedal is pressed less? http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html-----------
Brake pedal stuck? http://howtobyme.blogspot.in/2012/03/brake-pedal-stuck.html

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Car only starts when gas pedal is pressed? http://technoanswers.blogspot.com/2012/01/car-only-starts-when-gas-pedal-is.html

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Car won't start without hitting the gas pedal? http://schematicsdiagram.blogspot.com/2011/12/car-wont-start-without-hitting-gas.html

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emits whitish bluish smoke and bad fuel smell from exhaust

http://schematicsdiagram.blogspot.com/2011/12/van-emits-whitish-bluish-smoke-and-bad.html

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White smoke and Acrid Smell? http://whoisbyme.blogspot.in/2012/07/white-smoke-and-acrid-smell.html
---------- Car stalls and throws white smoke from exhaust? http://repairhelpcenter.blogspot.com/2012/01/car-stalls-and-throws-white-smoke-from.html

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This will help.
Thanks.

You need to have the brakes inspected. This noise is the brake pad wear warning tab hitting the brake rotor.;

Might want to check your motor and transmission mounts.. do this by turning the car on holding the brake and shifting the car into Reverse... with the brake pedal still pressed, try reving up your motor a few times and feel for a thunk noise do the same thing in drive.

Check if there's any Leakage underneath the car and all around the brake hose or galiper/drum, maybe you broke a line or busted a seal in a galiper or a brake cylinder if you have rear drum brake, when you did hit really the brake pedal ! Or check if there's any leak near the Brake Master Cylinder, it could be a bad Brake Master Cylinder ! Check if you didn't Loose a Pad too.. !

Is the noise under the hood? or where?

If under the hood, most likely the engine has a bad motor mount. The engine will "twist" slightly to one direction when driving forward and "twist" in the opposite direction when you drive in reverse.

When it is twisted (in reverse) an engine pulley or fanbelt is scraping on some plastic part, or whatever, and making the noise.

If not under the hood, it may be one of the front brake pads that have a "worn brake pad" sensor. The sensor is an L-shaped piece of metal that scrapes the rotor when the brake pad backing gets too close to the rotor, hence worn brake pads.

If the noise is somewhere else, maybe another "expert" has a suggestion.

Please post more information... Thank you.

Hi there,
when the noise is heard, try putting very slight pressure on the brake pedal and see if the noise goes away. If this is the case then definitely the brakes have to be removed and checked again. But if the noise is still present then it's something else doing that noise ans further investigations needs to be carried oput.
Cheers

shot in the dark but you may want to check your shocks