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I have just realised that the BOV on my car is not working at all. I'm pretty sure it's a HKS Sequential. I had thought (since i've had this car straight from Japan) that it was working, as the car emits a loud whistle when the accelerator is lifted - this turned out not to be the BOV though, as the car still makes this noise with the BOV completely removed from the engine bay and a straight piece of pipe put in it's place.

I have read literaly about 50 threads to try and find out what's wrong. Have already tried the adjusting screw on the back of it and even wound completely out it does not seem to work at all.

All i can think is that vacuum hose that runs in the top is not connected to the correct place.

In the pic it's where it was when the car arrived - is this correct? it currently joins the top (thicker) hose of the 2 that run to the front of the engine bay. Should i try another location ?

My intercooler piping does not have the little piece on it that lets the hose connect to it directly.

post-23664-1137409330.jpg

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So i guess that this (in red) is the stock blowwoff valve?

Why the heck would they leave it in if they install an aftermarket one too!!??

Is this easy to remove and block off the pipework where it's attached? Really want it off as it emits a LOUD whistle noise when the accelerator is lifted which is damn annoying.

Some of the things done with this car (straight from Japan) absolutely mystify me ( the JIC coilovers being the first - which were so friggin hard it's not funny and are now replaced with a set of Bilsteins:) and the set of actual large box stereo speakers sitting on the rear seat hooked up to the radio ( i have photo's as proof of this one) - what were they thinking?!

post-23664-1137463028.jpg

Yes you have two blowoff valves which is totally unnecessary. The standard one is all you need. The only reason I canthink of why the aftermarket BOV isnt opening is that is may be siezed, or the vacuum line has a leak or there isnt enough vacuum to reach it because of the first BOV? The reason why thay have left the standard BOV in place is so it remains plumbed back to avoid running rich I think??

Thanks for they reply LANFOH. I can't believe they wanted to avoid running this thing rich as according to the Apexi RSM the air fuel ratio's don't actually ever get above 10:1 and most of the time sit at about 8:1 - i am getting this tuned with the next two weeks (i'm they guy from a thread a couple of months back that gets only about 200kms to a tank).

Still would rather remove the original one if it's at all possible due to the high pitched whistle it makes. Does anyone have any info on how to do this and block it up easily?

as an experiment could i place a block in the vacuum hose for the stock BOV - this should then stop the stock BOV working altogether and the HKS one will work instead?

Then if i decide i do not like the HKS one or the car does not run well, just remove the block to the stock BOV and the HKS BOV completley and be back to normal.

For anyone curious - i did as per above with the vacuum hose to stop the stock BOV opening and let the HKS one take over.

It worked.

Car makes a flutter noise when released at low revs and a loud whoosh at high revs.

I have now decided that this is all too loud for me so the HKS BOV will be removed completely.

Thanks to everyone who help me figure this out. And i have a 2nd hand HKS BOV for sale if anyone''s interested:)

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