well, thanks, i will check it out tomorrow, i just dont want to break anything if it's delicate. Does anyone know of any 3rd party machinists that make a better (possibly alloy) version of this now plastic shaft?

 

dont trust the 1st gear or second gear pull to readline... the torque load can seriously hide any VIAS problems especially if the VIAS has been broken for a long time. Like I said, push the VIAS actuator under the VIAS component and see if there is a lot of vacuum pressure which might make it difficult to push. If it feels easy then that means the rod inside the manifold is not rotating. But since you are at 40k, I would check it anyways. If it is working, reinforce with jbweld since it is open.

 

The case is plastic, but all the rotating parts are metal. This is not a readily serviceable component (wish it was), so a machine shop wouldn't be able to help.

 

There isn't anything that's really "delicate". The only thing that might give trouble are the 4 mounting screws for the VIAS actuator. But if you follow my suggestions in an earlier post in this thread (Post #59), they should come out no-problem.

 

There is enough vacuum resistance against the shaft that it's really to hard to tell just by rotating it. If you suspect failure, the only 100% sure way of confirming is to remove it.

 

yeah, you can't tell accurately without removing the box. Maybe if you remove the locknut holding the VIAS actuator and pull off the lever for the vacuum actuator and the lock piece, you can turn/wiggle it... but why bother? Removing the screws gives you an opportunity to replace them with bolts

BTW, to regurgitate what SR20DEN said in another VIAS-related thread, the bolts you use are M6x1.00 thread pitchx20mm length, 10mm head (I used 16mm length since NAPA was out of 20mm, and they work fine). Use an M7 washer (though NAPA didn't have any, but they did have 6mm washers which worked just as well)

 

You guys are gaining acess from the throttle body side if I am reading correctly? If so, I am going to take it apart right now an fix it. I have JB weld in my basement, so I will have to go to NAPA and get new bolts.

 

Yes, from the drivers side. Also, I had zero problems with the screws, so I just reused them, maybe I was just lucky though...

 

I had no trouble with the screws until the 6th time I opened it or so

(I looked at it a few months ago... didn't catch on to the free play in the cup being a problem)

 

Thanks, I have the intake off, so I might as well fix it. I am working on the strarter right now. It shouldnt take me long to get the VIAS fixed. Is it alright to re-install the rod with the JB weld on right away. I would let the car sit for 24 hours to let it dry, so I figure it should be.

 

With JB Weld Kwik, let it sit at least 1-2 hours before installing. That worked for me.

With regular JB Weld, you should wait longer.

 

You do have a point, but turn the rod before and after fixing the VIAS and you can tell a serious difference. But I guess this test is only good if you already know the difference of pressures.

 

Anyone have any suggestions for my previous post?

I'm going to inspect mine, if there is a problem with it not opening up correctly, should I pull it out, or jb weld it. I have i/h/e with no cat/udp and i removed the restrictor plate behind the tb. Will i lose too much torque if i just remove it?

 

too much torque is in the eye of the beholder. i think the dyno of madmax was a loss of around 15lbs of torque throughout the whole band . it gained pretty well up top but i dont recall a ballpark figure. if i were you, id just open it up and put the jb weld regardless. my plan of action is to open it up, use the jb regardless of its condition and just hope that something is wrong so i will feel a gain and replace the screws with bolts.

 

The only way that the removal of the rod would be beneficial is if you had a higher rev limit (maybe even more than TS ECU can do at 7+ rpm). The more optimal setting is to have the VIAS working.

 

This really should be a Nissan TSB procedure. Makes me wonder if Nissan did this intentionally to make the Maxima run slow as it gets older... thus prompting the owner to buy a new car

Nah I doubt it, that's too conspiracy theory-like.

 

There's really no reason to remove the rod, unless maybe you're turbo- or supercharged and going for all-out flow (and don't mind some serious lack of low-end...)

Also makes me wonder if it's worthwhile for T/C or S/C'ed VQ30DE-K's to hotwire the VIAS control solenoid to an RPM switch of some type and tune the RPM at which VIAS engages... for maximum airflow (low setting for good low-end torque, then switch to the high setting under boost)

 

Didnt get a chance to try this today, but did you guys remove the throttle body? Also, I tried to loosen the screws and the bottom 2 were stripping real easily. What did you guys use to remove them?

 

I did remove the throttle body. If your screws are stripping easily, BE SURE you have replacement bolts available (M6x1.00x16-20mm, 10mm head, 6-7mm washer, 4 of all of these), then try using locking-jaw pliers, or an impact driver of some sort (I think Sears sells these... you can put a philips head bit in it, position it on the screw and strike it with a hammer, acts like a poor-man's impact screwdriver)

 

I will go to NAPA and buy the bolts tomorrow sometime, then try some vice grips. How long did it take to get the throttle body off.

 

Sloppy is right. With the vias broken, I dyno'd at 178 fwhp and 198 torque. After the valve was removed I dyno'd at 203 fwhp and 185 torque. Looking at just these numbers, It looks like a good tradeoff. However, looking at dyno sheet, my torque AND horsepower were down signifigantly until about 4900 rpms. and besides, I am not aware of anything that we can do to raise our rev limiters, and if anyone knows otherwise, I would love to know. Anyway , long story short, the VIAS fix is the best way to go.

 

You can skip removing the throttle body by just holding the throttle cams back.

 

Gotcha. This is with the Power Valve removed COMPLETELY, right? So a properly working VIAS would give you mad torque and a very decent amount of horsepower... just not quite the amount you got with the valve removed

 

my dyno for an auto was pretty strong on torque for my mods at the time but the horsepower was lower than i expected. i think i dynoed 178hp and 189tq but my hp increased at the vias switchover but not at the rate as most others. anyways, that was over a year ago and i should be doing the vias fix tomorrow along with my oxygen sensor fix after the headers. only 1 secondary o2 is currently working, haha. ill post up if i feel any difference and a new dyno should not be far to take the guess work out of it.

 

Yeah, This was with the valve completely removed. This dyno was done with a very dirty air filter, bad coils and spark plugs with 55k on them. I have since cleaned the filter, changed out the coils and plugs, removed the throttle body restrictor plate and advanced my timing to 17.5 degrees. I plan on doing another dyno soon. My mods are listed in my sig. I would love to do this dyno with cattman headers, but funds are a little short. I believe that I could get AT LEAST 215 fwhp with the headers. This (not having a valve in at all) would be absolutly awesome situation if I could just bump my rev limiter to 7500 rpms.... But I've recently heard from a good source that technosquare has run into a few problems trying to reflash our ecu's and that their efforts have almost completely been stalled. There goes that idea.

 

Do you know what hp you will be around at with a working vias?

 

were there any original threads about this and about how to take it apart and how to check if u have the vias problem?

Sorry, id do a search, but im not a donatingm memeber :/

 

Alright, I did the fix this weekend with Kevlo911, and he thinks we fixed it, I however was skeptical as to whether or not it was broken, since I just got the car. It pulls the same after 5,000 as it does up to 5,000. Doesn't fall off any, but it doesn't pull extra hard either. From the way kevlo was talking, it's supposed to be kinda like VTEC on a honda, and noticeably change the sound of the intake and pull harder past 5,000. There was a little free-play in my cup, but not that much. We still applied a little JB Weld Kwik. I am unsure on what position the white plastic rod that goes in the cup is supposed to be. While we had the VIAS off, the rod would rotate freely, and you could slide it into the motor about 2 inches. Does it matter, or will that automatically go to the correct position? I will probably take it back off saturday to re-inspect once I'm a little more clear on how things are supposed to be.

 

I would imagine that the maximum hp in a working vias would be very similar to the max hp of an engine without the vias, maybe just a couple of hp lower. It really depends on the car and what mods you have....
This thread (http://forums.maxima.org/showthread....2&page=1&pp=30) shows Maxgator dynoing at 203.7 hp with just minor mods and a functioning vias.

 

Look here...http://forums.maxima.org/showthread....2&page=1&pp=30 and read all five pages, it will be very informative.

 

you might as well JB weld it cause it will prolly break anyways (since that is just a stock manifold)

 

The power valve doesn't have any kind of mechanism to self-reset itself; it is completely at the mercy of the actuator in that little box. Assuming that you JB Weld'ed the cup in its center "resting" position, you should be fine.

I was thinking the transition is supposed to be like VTEC too, but it wasn't. It just pulls consistently hard all the way to the redline. In my case, since mine was fairly worn, I ended up feeling torque gains all over the powerband. If yours wasn't, you might not notice a difference. BUT, you can rest assured that it WON'T break now

 

yeah the vias won't give vtech or vvti-l feelings of high rpm pull because our vq is more refined than the those engines lol. I think, if i remember correctly, out powerband is much smoother anyways.

 

sr and i did the fix on mine last night. the rod was turning but the cup definetely would not have taken much more abuse. the cup wobbled freely but was still somehow planted at the bottom. i used the kwik stuff and replaced the screws. i plan on checking it in a week or so to make sure the jb held. as far as a difference, its hard to say since i replaced a bad primary o2 sensor @ the same time and when i left it was about 15 degrees cooler outside. car feels great though and i feel better knowing that i got it before it broke completely.

 

Does anybody have pics of the valve as you should put the JB on? I know I have this problem as I get an irradic operation above 5K, kinda like a surging sometimes so I believe this problem applies to me. I have 37K on the car.

I run my "test" in third gear. Sometimes its a nice pull to top...sometimes it feels like its choking.

Since if you pull the valve out there seems to be no point of reference to "align" it to put the JB on.

I looked at that one page of a million pics of the valve, but still seem a bit foggy.

 

thats actually one of the few pics i got. one before the jb and one after. if someone doesnt get one up first, ill download the camera then upload it tonight.

 

Thanks!

Looks like I have something to do this weekend in between thinsetting and grouting my tile floor...

 

The cup on mine didn't spin all the way around, so I picked the midpoint between its two extremes... which it seemed to "fit" into rather well for some reason. Looking at the face of the actuator, the cup sits around 4o'clock.

 

So are you saying we really wont know the "stock" position of "off" and the stock position of "on"?

 

I guess if you want to get technical, no, there's no notch in the manifold that says "CLOSED" and "OPEN." The only sure way to know is to remove the manifold, remove the power valve and inspect the insides to see where fully-closed is. But I noticed what felt like a "notch" inside the cup when I rotated it where it seems to rest. I'm assuming this is the fully-closed position, considering that resting position is coincidentally RIGHT in the middle between the 2 extremes.

If you know where "fully-closed" is, that's good enough because the mechanism is already designed to rotate the power valve by the right amount to make it "fully-open."