fluttering noise from the intake

[turbo3.8monza]

I "borrowed" my dad's 98 Regal GS the other day (was to tired to climb through the cage of the Monza). I was sneaking away from the house light on the throttle, not barley moving but right before it started making boost. I heard a fairly loud fluttering sound from the intake, I installed a fender well intake a few months ago as a suprise to my old man (thats why he doesn't mind borrowing it every now and then I keep it running in good working order for him). The noise is only present during light throttle, its not there when its making boost. I think its the boost bypass valve acting up but I want to make sure before I go off and replace it. has any body ever had this happen or is it supposed to make this noise on light throttle

 

[38turbo]

my 98 gtp did that also never noticed it until i installed the cai
but it would only do it when the engine was cold at part throttle

 

[turbo3.8monza]

this one does hot or cold just right off throttle, I hoping it wasn't a warning sign that the bypass valve was dying

 

[aussie_buickV6]

greetings from Aus!, my holden/buick v6 did similar to this (although its not turbo yet) after spending about AUD$450 (356.95USD) on stuff I didnt really need( as the problem was still there) turned out to be a faulty coil on the coil pack which only playedup on low revs( taking off) changed the part cars been running sweet as since then

i hope this helps you out as it took me 5 days to find the problem

John

 

[turbo3.8monza]

greetings from Aus!, my holden/buick v6 did similar to this (although its not turbo yet) after spending about AUD$450 (356.95USD) on stuff I didnt really need( as the problem was still there) turned out to be a faulty coil on the coil pack which only playedup on low revs( taking off) changed the part cars been running sweet as since then

i hope this helps you out as it took me 5 days to find the problem

John

thanks for the advice but mine doesn't have a turbo, its a factory supercharged car (I wish I could convince my dad to let me convert it). the noise happens at any RPM's with light acceleration just before the the bypass valves closes