ok here is the situation. when fully accelerating at around 3000rpm as the boost pressure builds i will see it spike to 21-24 then immediately drop to 16-17 before settling at around 19. this has happened since i installed my k&n typhoon (yes i know its junk but i didnt know that when i bought it). i thought it might be the bov so i changed it to the aps bov. but now the aps bov has a whistling sound anywhere between 6lbs of vacuum to 6 pounds of boost if i let the car sit in that area. while on partial throttle. its not in backwards i know that. is there any reason for the whistling other than it not being adjusted correctly or it damaged? is there anyway to pressure test the whole system to check for leaks. ive run through a couple of times and looked for anything loose and couldnt find anything. Anyone have any suggestions or any ideas. any help would be appreciated.

thanks

 

anyone?

 

what kind of noise is it actually making? if its just a simple suction air sound then this is completly normal.. as that bov will be slightly louder then stock

 

do an air leak test. If you have an air compressor, the rest od the part will cost you no more than $20.

 

it actually sounds like a whistling sound like a whistling flutter at partial throttle. sounds like wen i put the stock one in backwards

 

my friend has the same problem i tried to help him but im clueless about it also

 

does your friend have the aps valve also?

 

^^^

 

the whistling sound is due to the valve being partially open.. I get it just off idle with a 1G valve when its just the right amount open..

if you remove your recirc hose and feel the valve (plug the hose to the intake) you'll notice air blowing out of it..

Its actually somewhat normal, but its a matter of adjustment, you have to increase the tension slightly so it holds closed better on those transitions, but still opens when you want it to open when there's positive pressure in the pipe, and vacuum in the intake manifold..

The problem is you have to compromise, increasing the spring tension will allow you to hold a bit more boost, and won't flutter or squeak/bark/whistle as much at part throttle operation, but could lead to compressor surge.

When you reverse the BOV (this is a bad thing BTW) because of the design it makes it very difficult to vent, so it opens suddenly with a huge bark/squeak) the HKS SSQV works similar to putting a BOV on backwards, only it has a small primary valve that vents easily under vacuum to release enough pressure to allow the entire valve to open easily.

Anyway.. Before I completely confuse you, the short answer is you'll have to either have to adjust the adjuster so its holding slightly tighter, or use a heavier spring or shim.. you may find that it being partially open all the time is affecting your spool and sometimes blowing open at higher RPM when you hit that boost level that it breaks it open..

 

my friend has the type s

 

the "flutter" is basically slight compressor surge... is the valve adjustable??

 

Wow.. I overlooked this post.... Read this.. and that should answer your question... good answer

 

malibu jack did pretty much answer my question saying that it is somewhat normal, the aps valve has a "fine" adjustment screw i adjusted it and it didnt help the whistling but it did help make the car stall and as for the k&n i replaced the k&n intake pipe with the stock one and left the filter on, and it really helped with the boost flux, now the gauges spikes only once in a while but but it doesnt drop and settle it just settles on boost, which it reads at 20-21 lbs, before the filter with the stock airbox it would read the same 20-21lbs. (gauge probably reads high) but close enough, k&n engineers really messed up on their typhoon design, it has caused me nothing but problems, also flutter isnt as noticeable, unless i just quit payin attention to it