strange noise at 7 psi

[jeff13]

Hey Guys,

Got a 98 S13 Blacktop SR20DET with a sealed Blitz BOV with a manual boast controller set to 14 psi (it came with my frontclip) - No FMIC so I avoid driving it hard until I can get one. I usually shift or get off the gas at 7 psi or about 0.5 bars. I did a seach but really couldn't find anything similar. Here's the problem:

I push the gas down and there's a strange loud fluttering sound coming from under the hood starting at about 7 psi on the boost gauge. It runs fine until it hits that mark on the gauge. Its a constant and consistant sound that stays until I shift or get off the gas. I've looked around in there but can't find anything that could be causint it - hell, to be honest, I don't even know where to look. All the lines are ok (thought it was another leak) and the BOV seems to be working ok but is still my number one suspect. Any suggestions? I appreciate any input!

[jdm_master_X]

wastegate flutter?

[Hijacker]

9/10 chance that it's the gasket between the turbo and the exhaust manifold. the nuts can sometimes come loose and let the turbo hang low just enought to let some gasses out. The gasket ends up flailing about in the gap and causes that flutter sound. I've had it happen twice to me.

The only solution is not fun. Pull the turbo and manifold and retighten those nuts down.

One way to check is to try and rock the turbo and see if it rocks independently of the manifold.

[da40]

wastegate flutter?

i agree could be wate gate flutter or turbo , iknow mines makes aloud turbo flutter as soon asi let off the gas at any rpm.PS i have the gt28r bb turbo

[jeff13]

Thanks for the great input, at least I have places to start looking. I had a wastegate problem a while ago - i think it was stuck but it 'fixed' itself . . . I appreciate it and will update once i get some time.

[ILikeMy240sx]

If your BOV needs to be tightened, it will start to leak air and make that flutter noise you speak of.

Try tightening down the BOV.

[jeff13]

I'll check BOV but its sealed - nothing I can see to tighten . . . I could be wrong though.