The only time it stops, is when I'm on the throttle. Any time I let off, it just keeps on hissing. Sounds like a jet taxiing for takeoff.

It doesn't sound like a boost leak anywhere, so I think it just has to do with the Maxflow Bypass Valve. I haven't had a chance to get the car up in the air to check out the adjustments, but figured I would get your guys' expert input...

 

Its near impossible to diagnose over the internet.Especially with the limited information you have just given...Can you be more specific?Where does it sound like it is comming from? FYI A SC wil have certain amount of "Whine" at all times.

 

Try going from simple to complex.
If you don't have a by-pass valve filter, put one on and see what happens....

http://www.superchargersonline.com/p...ber=V8H040-175

 

Anytime you are under half throttle the bypass valve should be open and venting air. However, by the sounds of it you are having compressor surge and your bypass valve is not opening up at all. You really shouldn't hear much when the bypass valve is open except the initial release so my guess would be that it is surge.

Surge could be caused by a couple of things.
-Improperly hooked up bypass valve. It should be hooked up post throttle boy so that it sees vacuum
-Improperly adjusted bypass valve
-broken bypass valve


If the car is running fine and the A/F is correct I would assume that surge is the most likely diagnosis but possibly it could be something else.

 

that is normal, anytime you have the revs up and dont press the clutch in, it will hiss.

push the clutch in, the car is building boost depending on rpms. the air has to go somewhere if the throttle plate is not open

 

is this something that just started happening or has the vortech always been like this? Because the vortech will always vent air out when you're not on the throttle and close up the bypass valve

 

It's definitely not the usual Vortech whine/rattling you hear at idle. You don't hear the hissing I described at idle.

It's basically anytime you're off the throttle with any rpms. I'll have to see if it sounds any different when coasting with the clutch in. I guess I was a little worried b/c with a turbo setup, for instance, you only hear the blowoff right after you lift. In my case you hear it when you lift, and then it continues as you coast, until you apply throttle

So far, from a couple of your posts, it sounds like this is normal. I've only had the kit on for less than a week, so it's never sounded any different.

I guess I'll have to check the adjustment on the bypass valve. It came with a filter, which I left off, so I may also try putting that on to see if it quiets it down some...

 

If you don't hear it at idle then it is most likely the standard venting that you hear which should be anytime the bypass valve sees vacuum. The higher you are in the RPM's and close the TB the louder the hissing should be and it should get quiter as RPM's drop do to the reducing CFM flowing through the bypass.

 

is it the same sound like if you're on the highway at 70mph and let off the throttle completely? Because that's completely normal behavior to sound like a jet engine

 

Ahh...so it's normal then. Yes, the noise only appears while in vacuum. Ok, I feel much better now. Did some street tuning last week to get it running smoothly, but still need to do more fine tuning before I really push the car hard. Joys of buying a used kit and installing it yourself!

Thanks for the help peoples!

 

My bypass valve whistled at idle but putting the bypass valve filter on it eliminated that issue.

 

totally normal, you'll get use to it.

 

I honestly can't even really hear it on my car so much
my idle is pretty high and the exhaust is already pretty loud. All I hear is the engine and the blower really

 

I do need to raise my idle to try and eliminate a bit of that blower noise. Since you all seem to be very knowledgeable Vortech guys, what do you suggest I raise it to? Is it really necessary to go all the way up to 900? Also, how do you suggest I get that performed at?

 

900rpms and onward is where the blower noise will start to go away most of the time. It partly depends on what pulley you use. The 2.87 pulley might be able to get away with 800 rpms while the stock 3.33 pulley will probably need the idle set to 900rpms or higher for the rattle sound to go away

get it raised by having a dealer do it or anyone with a CONSULT II or better, get the cipher sold by AAM, get an ECU flash and have it raised, get a standalone EMS that can raise it

 

A buddy used a Cypher and raised my idle to around 850. Just adjust it until it sounds like you want it to sound.

 

i took my car to the dealer the other day and the service rep said that the tech's told her raising the idle would throw a cel and the ecu would adjust the idle back to the original position. i tried to tell them otherwise but they refused to do it.

 

lol dealers sure are stupid sometimes

 

They sure are. I'll have to figure that out later, I guess. Oh, I'm running a 3.12 btw.

Gilley: We're in the same boat now...ex-Stillen owners, haha...

 

That sound as described is the normal bypass release sound from the valve. It is present at all times unless under boost and louder as RPM's are higher (more air volume being vented). As mentioned by Gilley above, some of us added filters to the valve opening and this quieted it down quite a bit.