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Noise: Vacuum leak or a relief valve?

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Old 10-29-09, 10:33 PM
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Rotary Freak

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Noise: Vacuum leak or a relief valve?

I have a whistling noise when I blip the throttle both on engine acceleration and deceleration. I just reinstalled the emissions air control valve and air pump, since then I have been hearing a whistling noise like a gasket is not set so something... But I just reinstalled, cleaned, and added silicone to all the gaskets aside from the ACV to manifold.

Any ideas on this?
Old 10-30-09, 10:52 AM
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When the ACV relief valve opens, the air has to go somewhere (assuming it's not stock). How do you have it plumbed? It's been a while since I've looked closely at it.
Old 10-30-09, 03:16 PM
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Originally Posted by arghx
When the ACV relief valve opens, the air has to go somewhere (assuming it's not stock). How do you have it plumbed? It's been a while since I've looked closely at it.
The relief valve you are speaking of is on the ACV, right? If that is the case, the air should just go back to the intake, the noise is coming from around the UIM.

I had the UIM off about 8x already, checked everything over, I going to do it again and double check my vacuum line routing. The way it is set up is for simplified emissions, but I added the ACV back in plus the solenoids/air pump. The only questionable area was were the relief 1 (b) solenoid got its vacuum from, looked on the vacuum rack and it teed with the switching (c).

And looking at the vac diagram now, I may not have the check valve in there, I am going to add the check valve to the line (relief/switching) and see if that corrects it, it maybe sucking air thru the vent(s) on those two solenoids.
Old 10-30-09, 04:16 PM
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Alright so added the check valve, it still does it.... However this time I decided to disconnect the air pump, the whistle/noise goes away, its more like a screach for one second, both on engine accel/decel. The only gasket I did not add silicone too was the ACV, so I am going to tear the uim back down and once again recheck all the vac lines and proper routing....

I will have to see if I can get audio/video of the noise, maybe someone has come across this already.
Old 10-30-09, 05:33 PM
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Well the audio/video is not going to happen, I do not have camcorder, my dslr does not do video, and my phone is not a compatible format to be uploaded anywhere..... Listening to it again its more like a screaching noise... I know its hard to describe on imagine.... Could this noise be the relief valve opening in the ACV??

I checked everything (wiring and vac lines) over again its all good, I just added silicone to the ACV gasket, I will give it some time to setup and see what happens... But I do know its emissions related, seeing as when I disconnected the air pump wiring it stopped.
Old 10-30-09, 05:53 PM
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Looking at the service highlights book, the air pump is sending air to the cat for 300-500 secs on a cold start, which is about 5-9mins, perhaps the noise I am hearing has something to do with the air tube to the cat... However I added silicone to the gasket (the reusable metal type), and maybe I did not let the car run 5-9mins+ for that to shut off... I do know the cat got to somewhere in the 320 degrees F mark, which should be plenty of temp..... IDK I am trying to cover all my bases here. I do know, when I got the car it was stock and I do not recall any noise as such when driving, later I removed the emissions controls, going on 4 years, so maybe I was mistaken, or the fact that under driving conditions is different then idling the...
Old 11-01-09, 12:59 AM
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Turned out it was the ACV gasket, I guess the metal "reusable" are not really reusable, added silicone and all good!!


Took it for a drive tonight, DAMN! its been a long time!! So nice so fast! LOL.

Question, this is the first time I have a cone type intake, is it normal for the spooling of the turbos to sound droned out, kinda like its spoolin backwards,lol? I am thinking I am hearing more sucking from the intake then what I am use too.

Also I when I had the uim part the last time I was looking at the wiring for the turbo solenoids mounted on the front the UIM, I had them marked but witch connector goes where, the wiring looks identical on both of them... Or maybe its just dirty wiring.....
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