350Z400rwhp

iTrader: (4)

Well I have been having an issue with what I think is boost leak on my car. It will only boost to about 5 psi and I can hear a whistle sound once it hits 5 psi while under full throttle. I capped off my exhaust (4" rubber caps) and connected a 2" pvc end cap to the coupling that attaches to my supercharger. I then added pressure through a valve stem for a car tire that I put in the pvc end cap (See Pics). I attached the air hose and tried to add pressure but it wouldn't even take. Immediately I found a major leak on my intercooler where the bolts go to hold the bracket. I put some nylon tape to a bolt and put it in the hole and I figured the problem was solved. I also found a leak on the elbow fitting on my catch can but it was very minor. I took the fitting off and put some nylon tape on it but there was still a minor leak. I also noticed a sound coming from a sensor or something on the back of my engine (once the system pressurized to about 7 psi) that had a tube coming off my intake manifold where the throttle body is attached. I was able to pressurize everything to 9 psi and once I let off it slowly lost pressure and after about 15-20 seconds it was back down to about 4 or 5 psi. I figured this was a very minor pressure loss and would probably be fine. I took that car out for a drive and expected to have a major improvement but I still have the exact same issue and it only boosts to 5 psi and I can still hear the same whistle. I will post a video of this later tonight but I guess my question for now is, should my system be completely air tight? So if I fill it to say 9 psi should it stay that way and lose no air at all. Any ideas on what is going on with my car and I already did put a new belt on my supercharger and it's nice and tight. Thanks in advance....

JonnyC

iTrader: (19)

Is the leak coming from your bypass valve maybe? Is the vacuum line going down to it good? Have it adjusted right?

That's all I got

350Z400rwhp

iTrader: (4)

The bypass valve is the next thing I am going to try and check. Would it react differently from pressure from the supercharger vs the way I was pressurizing the system? I mean it held at least 9-10psi when I was checking it today without any hint of leaking. I can't believe the first leak I found on the intercooler wasn't the problem as it was leaking out air as fast as I could pump it in with my air compressor and once I sealed it I was able to pressurize my system.

merlin3

iTrader: (4)

I wouldn't pressurize past 5 lbs, that's usually what's recommended when doing a boost leak check, you're going to risk doing damage if you do too much.

350Z400rwhp

iTrader: (4)

This is the part that has a hose attached to the manifold that was making a gurgling sound at about 7-8psi when I pressurized my system. There is also a video of a second gear pull. Notice the whistling sound that can be heard along with it only boosting to 5psi, could this be the bypass valve? http://www.youtube.com/watch?v=VC9Q_xk4mrE

wannabuy350z

iTrader: (27)

does sound like the BPV. maybe its leaking under load

350Z400rwhp

iTrader: (4)

Would it stay sealed when I just add the air through the valve stem when I did my pressure test but leak when under load from the supercharger? Here is a pic I took of my bypass valve, not sure if anyone can tell if it is bad or not from this.

350Z400rwhp

iTrader: (4)

Video, may need to listen to it twice to hear the whistle sound. http://www.youtube.com/watch?v=VC9Q_xk4mrE

rrmedicx

iTrader: (54)

Probably one of your couplings is partly off or broken? Double check all of the couplings, perhaps one of them has a crack. Check each thoroughly. Sounds like a bad boost leak.

Fidanza

iTrader: (5)

I get the same sound but it is never under load. Air is blowing out of the bypass valve and hitting the front sway bar. Put it up on ramps, took off the under skin, put my hand in front of the valve and sure enough the whistle stopped, so I put a small piece of DEI's Boom Mat on the sway bar and the harmonics stopped, whether or not mine should be doing that who knows. But it sounds like you have the same thing but mine is at idle , sounds just like bad brakes.

booger

iTrader: (6)

I hear the leak in the vid . When I did the preasure test I found leaks and sealed them . I set my compressor at 40psi and saw 20 to 25 psi on my gauge in the car . If your BOV is leaking by , you would be able to hear it with the compressor hooked up . Preasure is preasure...doesnt make a diff if its from a air compressor or a SC .

Keep sealing the leaks up till there is no more

osinrider04

iTrader: (6)

my friend just found a leak on his 240 because the male parts didn't have those little nipple covers.

Barzten1

iTrader: (18)

Dude that happened to me once and I couldnt figure it out. I finally just started tightening bolts under the hood and I tightned one of the plenum bolts and it went away. I loosened it and it came back. Id try tightening the plenum bolts.

merlin3

iTrader: (4)

I'm not sure where you're pressurizing the system from but the reason I said don't go over like 5 lbs is because you can be pressurizing parts that never see positive pressure and you can blow seals. Be careful what you're doing.

350Z400rwhp

iTrader: (4)

Thanks for all of the input guys. The leaks that I have at this point are very minor. The part on the picture where I have my finger pointed, can anyone tell me what that is? I was thinking of crimping off the hose going to it as it is gurgling under pressure and may be a source of boost leak. I also have a small leak where the plug meets my maf sensor but once I get past 4 psi it stops leaking (kinda weird). How air tight should everything be? I'm able to pressurize my whole system and it will hold pressure for at least a minute. I guess my question is that I am bleeding off like 5lbs of boost, I would expect a fairly large hole to cause this and my system seems to be nearly air tight.

350Z400rwhp

iTrader: (4)

If I want to tighten the blow off valve so it holds more pressure which way do I want to turn the screw. I have 6-7 threads showing after the nut on there now. Should I take it out to 8 or 9 threads or tighten to 4 or 5 threads showing?

booger

iTrader: (6)

6 or 7 is as tight as you wanna go . loosening or tightening up that bolt only adjusts when it opens and closes . That BOV has held over 20psi for me . As long as the diaphram is ok , it will hold !

350Z400rwhp

iTrader: (4)

Well guys I am really stumped. I'm just going to review the facts and discoveries one last time and would appreciate any input. Tomorrow I am either a. Going to drive this thing off a cliff and be glad I purchased gap insurance when I did my financing or b. Call a shop with a dyno and start throwing cash at them to try and diagnose this problem on a dyno. If this mystery goes on after that my stuff is going up for sale and I'm just going to buy a Vette and call it a day.

1. Car has seemed to be getting progressively slower over the past couple of weeks. I have shrugged it off as "getting used to it" but there has been something going on.

2. I pressure tested it yesterday and found a screw hole where the bracket is attached to the intercooler bleeding off a ton of pressure and figured this was the cause of my problems as I couldn't even pressurize my system as if would bleed off air as fast as my compressor could pump it it. I put a bolt with nylon tape in this hole and no more air leaked out of it and I was able to pressurize my system. (I still can't believe this didn't fix my problem)

3. I pressurized my system (From the coupling that attaches to my supercharger all the way to my exhaust as I capped my tail pipes with rubber 4" pvc end caps, see pics at the begining of this thread) There was a sound coming from my plug connector on my maf sensor at around 4-5psi but was very minimal and stopped as pressure increased. There was some gurgling coming from a sensor that has a hose coming off the manifold into it at about 7psi and up (I have a pic of this also but still have not been able to figure out what this is and if its normal for it to gurgle while under pressure or it I can pinch it off to eliminate from the equation). I had a slight leak in the elbow of my oil catch cat but I have since bypassed the catch can altogether and just have a hose in place of it to eliminate the oil catch can from the equation.

4. I pressurize my system to 10psi and it holds fairly well and slowly loses pressure and after about 20 seconds it is at 5psi and back to 0psi after about a minute. Nobody has said that my whole system should be air tight as I would think this would be nearly impossible, but should it be air tight?. The leaks that still remain are pinholes at best and I find it hard to believe that I am losing 5psi of boost out of a pinhole leak.

5. There is a whistle sound when I drive the car and try to hit full boost (see video above). Still can't imagine how as my system is darn near air tight.

6. The car runs fine with no ideling issues or driveability problems.

7. Belt is brand new and tight.

8. My supercharger sounds completely normal and is making no unusual sounds.

9. My bypass valve looks normal on the inside (See pic above) but I have not taken it out and fully inspected it as I don't want to add a problem if I mess the gasket up when removing it. My vacuum line is connected and it is showing 6 threads now and was showing 7 but I turned it in one earlier to see if it changed anything but it didn't.

So basically I am asking for some final advice on this before I get a shop involved that I personally feel may or may not have a clue about how to figure out what is wrong with my car.

One final note, could there be something wrong with my supercharger even though it sounds fine? Thanks in advance!

I really like this car and I have put a lot of work into getting everything put on when I installed everything a month ago so I really hope to figure this out or all of you are going to have some great deals to look forward to on my supercharger kit and parts

merlin3

iTrader: (4)

It is not going to be completely air tight, pressure is going to gradually bleed off. Like I said before I also would not be pressurizing it to that high of pressure. It sounds like you pressurizing it backwards which could potentially blow some seals that were not meant to be pressurized that way.

350Z400rwhp

iTrader: (4)

How am I pressurizing it backwards? Booger pressurized his to 20-25 psi. I am adding air to the coupler that attaches to the supercharger and my supercharger puts out 10 psi.