weird noise at 5500 rpm and above

[sixxdeuce]

tonight my car started making horible noises at higher revs. At about 5500 rpm it starts making a noise that sounds like a long sputtering blow-off valve noise?. Its hard to pinpoint but sounds like it starts somewhere near the driver and moves to the back, maybe something with the exhaust? But at idle I cant detect any exhaust leaks or heatshield rattles. And at lower revs it makes a noise that just sounds like air escaping, but not loud like most exhaust leaks sound. Anybody have any ideas?

[quiksilvia]

vac leak somewhere or exhaust...have a friend listen while u rev

[sixxdeuce]

I will give it a shot but it seems like it only makes the noise under load

[quiksilvia]

that should make things interesting...

[sixxdeuce]

the noise seems to have gone away and when I kick my muffler it sounds like it has small bb's or something in it. My best guess is that some metal from the straight pipe through my 2nd cat broke loose and rattled its way to the back. This happened to me once before.

[quiksilvia]

good to hear

[gore]

high pitch squeals at high RPMs usually means the fan clutch, I had this problem, so I replaced it, even now I get it to squeal if my car isnt warmed before I rev hard.

[quiksilvia]

u shouldnt rev hard till its warm anyway

[deftdrummer]

my car makes that blow off valve noise off and on too. I think its an exhaust leak. That combined with a big chunk of metal or something in my second cat makes for splended audio effects when i drive around town.

[sixxdeuce]

Well this started happening a week after I installed a header, but all the flanges, bolts, o2 sensor, and egr are tight and I cant detect any leaks at idle, even with the higher idle with ac on. I guess I should get a stethascope to listen in all the areas I cant get my head close to. The more I hear it the more I think its the straight pipe has cracked or part of the weld broke off, I just used regular steel piping and I think the cat shell is stainless so the metals dont bond as well as they would if they were the same, plus that thing gets super hot in there and expands, then contracts when it cools, it can deteriorate after awhile.