Hiss Sound When Steping on Gas

[JohnnyG44]

2003 Silverado 5.3L When I step on the Gas to accelerate I hear a hiss sound from under the hood, It only does it when I first step on the gas. If I just hold it steady no sound. I feel like I've lost a get up and go

[j cAT]

Originally Posted by JohnnyG44

2003 Silverado 5.3L When I step on the Gas to accelerate I hear a hiss sound from under the hood, It only does it when I first step on the gas. If I just hold it steady no sound. I feel like I've lost a get up and go

have an another person step on gas while you locate source of noise.
then repost results.......

[JohnnyG44]

it only happens when driving not when sitting still, if sitting still it revs just fine..

[sierra99]

Originally Posted by JohnnyG44

2003 Silverado 5.3L When I step on the Gas to accelerate I hear a hiss sound from under the hood, It only does it when I first step on the gas. If I just hold it steady no sound. I feel like I've lost a get up and go

Are you the original owner of this truck??...The reason I ask is becuase I have the sam ehissing and is caused my me adding a vortec or tornado intake add on before the tpi....I added it about 80,000 miles ago and realize from all of the reading that it does nothing , other than hiss. Take a look for the add on....

I am too lazy to take it off....

[j cAT]

Originally Posted by JohnnyG44

it only happens when driving not when sitting still, if sitting still it revs just fine..

do you think the transmission is slipping? what is vehicle maintenence history ? any aftermarket modifications..............

[JohnnyG44]

transmission not slipping and no modification same as when bought it new and original owner. when I step on gas it goes pssssst when I
off or hold steady nothing. seems to lack that burst but still runs strong. I tried to test it while I was sitting in garage but only happens when driving when I need a burst of gas.

[j cAT]

Originally Posted by JohnnyG44

transmission not slipping and no modification same as when bought it new and original owner. when I step on gas it goes pssssst when I
off or hold steady nothing. seems to lack that burst but still runs strong. I tried to test it while I was sitting in garage but only happens when driving when I need a burst of gas.

muffler baffles loose? at first i thought exhaust leak but only when under load in gear this makes a psssst noise.......with vehicle in gear and foot firmly on brake if you rev engine does it make noise? if not then the noise is from drive train. check drive shafts and may be heat shields loose