Check out these of the Power Valve, what actually opens/closes at 5000rpm:
http://www.cardomain.com/memberpage/419735/12

I'll be adding more soon, but these are just to get you started.

Coming soon, DISproving the myth that 2K-2K1s VI/VIAS has TWO sets of runners.

 

Very neat. So, what part actually breaks if the VIAS is malfunctioning?

 

No sure, but if the L-shaped rod is turning, it's either the metal collar or the keyed end of the power valve.

I don't see what else could break.

 

we aren't special anymore.

 

Sorry for a novice question, but what does it do? How does it improve perfromance exactly? Which years have and don't have it?

 

It's the infamous power valve from inside 2000-2001 variable intake manifolds.

It's what you feel change at 5000rpm and the cause of the rush/pull to redline.

 

subscribing

 

i love that rush to redline, i can see the RPMs going up faster then at lower RPMs

 

IceY2K1:

I wanna feel that "rush" after 5200 RPM, I am pretty sure I am not feeling it (in fact, I feel a very subtle "jerk" around 5200RPM--that's another sign the VIAS isn't working right?). Hmm, work on car or go hiking today. It's gonna storm, so I think I'm gonna work on car today

 

ice, is there a sure way to tell if this is malfunctioning? do they go bad often? what's the fix?

sorry for all the questions but i just got back from the dyno and results weren't good. In fact, looking at the sheet, my horsepower curve peaks @ 4800 rpms, levels off and stays flat until 5800 then drops off again. Max wheel power: 178 max torque:198. needless to say i'm very dissapointed and unsure why figures are so low. need some ideas. thanks

 

Actually, I found the thread talking about the vias. Going to test it out soon.

 

I just inspected mine and took some pics. I see how the vacuum/fresh air is routed now. Still not sure about the vacuum check valve... I pushed a small straw (from a can of STP silicone spray) through it and sprayed in there a little to lube it up, still not sure if it's working properly 'cause I still don't feel the VIAS working.
I'm going to do another test to verify the L-shaped rod is moving properly under no load.

 

An experiment you can do if you have a stock intake:

1)remove your air filter and air filter holder.
2)Drive and run it to redline. The sound should change into a snarl@5,200rpms (switchover), if it sounds straining, like something is about to blow apart, your VIAS isn't working. Remember the sound, thats the key!
3)remove the plug from your black box located to the right of VIAS
4)Drive and run it to redline. If your VIAS is working, it should now sound like its straining. If its not working, the tone won't change.

This will also work with those with an aftermarket Intake. All you do is just skip step #1 and go straight ahead to step #2

Another one is to pull on the throttle cable to make the engine rev past 5,200rpms. Look at the black box, there is a rod with a rubber covering on it, that SHOULD move/turn if VIAS is working. Its much easier to have someone hit the gas for you while you look at it.

 

Wonder where you took those pics from

 

How many pieces did you want that manifold back in?

 

Can post a picture of the sheet?

What gear did you dyno in?

 

You aint tell me you was going to rip it to pieces...

 

It goes back together...no problem.

Just six screws on the IM and four bolts on the TB.

Piece of cake really. Easy to do on the car even.

 

man installing a VI is gong to be a challenge for me?

 

I can't post the sheet as I don't have a digital camera or a scanner. The dyno was done in fourth gear. I wasn't expecting a hugh horsepower #, but, with my intake and exhaust mods, I would hope to be at least at STOCK horsepower.

I'm still looking into what went wrong. I think that it just might be the vais. By looking at the dyno sheet, I definatly do not gain any power after 4800 rpms.
Thanks

 

Sounds like a VIAS problem, see if the L-shaped power valve rod turns, when you rev it past 5000rpm.

Honestly, those numbers sound weird though. Torque peak is 198ft-lbs? That's high, that's why I was thinking you did it in the wrong gear.

Somethings wrong either dyno or VIAS IMO.

 

More pics available here-- http://spirilis.net/gallery/vias-teardown

I was mostly interested in understanding how the vacuum flow occurs to the Power Valve. I think I have it figured out, although there's one part I'm unknown about. It's not visible in the pic, but on the manifold itself there's a square opening towards the lower right... I'm not sure what that is, since it is exposed to the rest of the "vacuum tank" portion of the assembly. Maybe it's just dead space and is a volumnous part of the "vacuum tank"?

Either way, I know where this "check valve" is. It's the small black opening at the top with the red piece inside. I was able to poke through using a straw from a can of STP Silicone Spray, and I sprayed a little in there (and got a little inside the manifold too) just to see if anything different would happen. Didn't notice any difference in operation. But I'm still pretty certain my VIAS isn't working properly. I'm going to look at it further soon.

 

Ice didn't Dixit send you an email on this thing? You're holding up R&D.

 

update: I did some research on the org and found max_gators thread 2 years ago about his failing VIAS and his dyno sheet proving the failure. :sigh:
My problem is EXACLY the same. Our dyno's are a perfect match. I now know that my VAIS is not functioning properly. The bad thing is, it's not the vacuum line. I did the test where I rev'd the engine past 5000 rpms and the L-shaped arm activated. So visually it looks like the VIAS is functioning, but my dyno says otherwise. Max_gator's situation was the same. The solution for him was nissan fixing it by replacing his variable intake under "customer goodwill". My problem is that I doubt that my nissan stealership will fix this problem for free. Has anyone fixed this problem on their own since Gator's incident?
Thanks for the help. And thank god for the org, I would have never figured this out without it.

 

Yeah, Thaniel clearified that's the vacuum tank.

 

Yes..........

 

Spirillis,

Have you made any progess with the VIAS? Keep us posted. Thanks

 

Okay...that's the last of them.

 

hmmm i need to ck mine

 

No progress on anything mechanical, seeing as I'm busy with work... HOWEVER

I have confirmed my VIAS is not functioning. I disconnected the VIAS control solenoid this morning and drove it to work, and I did not feel a SINGLE difference in performance from yesterday. RPMs continue to climb above 5000 RPM at the same rate as I recall yesterday coming home from work.

 

spirilis,

You need to use a stopwatch and a long stretch of road.

I'd put it in 3rd and set the cruise to exactly 60mph, then hit the stopwatch and gas at the same time and time yourself to 100mph or at least a mph above 6000rpm. Repeat with VIAS plug disconnected.

Or if you have a Gtech Pro...that should notice. I might try that once I get mine back, ie do a HP measurement withOUT VIAS and with and some 1/4 time runs. It will be awhile though.

 

I can try that sometime just to verify for sure.

 

Yeah, if there's not a drastic change in time, you know it's not working.

 

VAIS problems eh? Interesting.

 

yea... VAIS problems here also

 

Larry...maybe you and Regime should meet up, he's in the "Fremont" area, I believe. He has a GTech Pro and could help diagnosis the VIAS possibly.

 

Didn't I see some of those pics in Health class in a movie called "The Mircale of Life"? j/k. pretty cool stuff.

 

you gusy ar having problem with it. i on the other hand want VI on my max.

 

Some of us do too

 

I know the secrets of the broken VIAS.