Pimpin' the VIAS fix, full time.

My VIAS explanation and fix

The .org VIAS thread

 

I haven't checked it yet, but it does pull hard and open up at about 4500 RPM so I think it's fine.

 

my dyno says its still working. However i've replaced one manifold already

 

Id rather not know, but its still pulling above 5k so its most probably just fine.

 

75k mi, 2k -opened it up about a month ago, it was fine no wear at all

 

Made a new cardomain site today with a VIAS page: http://members.cardomain.com/mhadford

 

Very nice write-up! Put a link in the 5th gen "how-to" thread if you haven't already.

 

JB Weld 4 lyf yO

 

My VIAS seems like it works because at 5000 rpm i start to pull hard on 4 gens.

 

Thanks ... I'll have my shop check this out this week!!!!!

 

just a few clicks after 50k, the cup was almost seperated. dyno @ about 35k confirmed it was working but at 50k, it was close to going out. used jb weld but have not checked since. seems to pull hard to redline.

 

140K and still working and looks fine.

 

You're welcome again guys.

 

Both links in your sig are exactly the same

 

Removed the power rod on mine last week, low end is little weaker, but hold on once ya over 5500-redline you will be amazed with the power increase at top end vs the broken cup. My car has seen alot of abuse, I'm talking 100K miles worth of redlines every day, NOS, road racing at road america etc. My **** was phucked. I will try to make a nice video to show off the true power of a DE-K.

 

Haven't checked mine either... but like others, the car is still pulling over 4500 rpms...

 

my dealer told me its covered under a 80k mile warranty. However good luck proving that the power valve inside is broken to the dealer. Nissan has no idea of this, the fsm test procedure is only a outside visual inspection

 

Haven't checked it but everything seemed OK last night for me except for the fact that the automagic would hold 6k rpms in 4th gear forever before i had to let off to get it to shift into fifth -- pain in the ***.

 

this isa little off topic,....
but a couple of months ago i had my instrument cluster off to replace some bulbs, while i was in there i put an LED into the "sport" suspension indicator light, thats in there for no reason.(and blocked the shock portion) then attached it to the ECU lead for the VAIS, so when the lead drops to 0v to actuate VAIS a little green "sport" light in my in my dash lights up. (i know , i was bored)

it usualy operates around 4.7-5k. but when i realy get the gas, or when my tires spin in 1st or 2nd b/c rain or ice, that thing somtimes opens up as early as 2.7k rpm, which i think is weird - b/c ist the benifit of the VAIS toward top end and sort of hinders things down at the low end?
I dont think its just my car, everyones probly does it as well.

SR20DEN perhapse you could shed some light on this

 

I cant say it enough how simply you put this whole VIAS problem. I am going to check mine out next weekend. Youre pics are perfect and written instructions are excellent. Thank you very much for taking the time to do this write up & take the pics. I am sure I am not alone in my observations of your write up. I allready printed these instructions up for safe keeping. Thanks again.

 

Good idea...wish I was more electronically inclined.

 

umm, sorry to tell you this but your transmission only has 4 gears if you are a auto

and the light to show that the VIAS is getting a signal from the ECU won't help because its the power valve inside the intake manifold that is not activating and that part has no electronics or sensors to it

 

Hmm, well I guess that means it was 3rd gear waiting to shift to 4th. Either way, it seemed as if it was taking way too long to get into overdrive.

 

I know what breaks, mine is fine i checked not to long ago, but to restate my question:

When the engine is running at low or medium RPMs, the valve is closed. increasing effective suction port length, thus increased air intake = improved suction efficiency and higher torque generation. When engine is
running at high speed, the ECM actuates VIAS which opens the
power valve to two suction passages together in the collector.
decreseing effective port length, thus decresed suction resistance and more HP.
So what is the benifit of the VIAS operating at low RPMs during rapid acelleration, when its purpose is to increase top end HP?

 

im taking out my "power rod" and doing some experiments

 

Just remove the power valve and see how your top end feels I had a hard time keeping up with a auto 3.5L on the highway at one point last month, and I always wondered WTF is up that my top end is gone. I fear no 3.5L on the highway from 80MPH up, sweet spot is right at redline Me needs 8K RPM fuel cut. I'm sure the power at 7500RPM would still continue to raise. SOB sounds NASTY without the power valve, and the torque and low end power loss is livable with as long as you aint no automatic. I'm gonna make a block off plate for my VIAS switching mechanisim and take the whole thing off- just need to figure out how to keep the CEL from coming on.

 

Hey,

Do we know how to fool the ECM into setting off thie VIAs a little sooner than 5500RPM? Maybe trip it at 4K? Maybe technosquare can do this in their ECM for us?

 

Its not worth setting the high RPM runners at lower speeds. I noticed with my power rod removed that power starts to come on strong at exacly 5400RPM- up. I think Nissan did their homework right and changing the runner switchover set point would just hurt your cars performance. There is definite loss in TQ and HP till 5K RPM with the power rod removed. I do alot of highway driving so for me the low end pull isn't as important. Car still accelerates pretty good in 5th gear. I still think I got more pull in 5th gear with the power rod out than a 4th gen I recently driven.

 

finally got around to take my power rod out today... my vias actually WASN'T broken and i atleast go to redline once a day!!! although my rod and everything else to do with the vias was covered in i guess blow by oil (it was caked on there) other than that it was fine! so far ive noticed slight mid range loss of power but other than that im ok (im a AUTO) it def. pulls harder past around 4800RPM.

-Anthony

 

say the vais open at 4000rpm or 3500rpm would that allow our engines to breather even better under exceleration for the auto max. i have a auto se and i rarely take it about 3500 rpm unles i need to get on it so if it opens up sooner would it make more power or would it make the mixture too lean?

 

your vq35de VIAS already opens at 3800 rpm

 

So Blackbird, I know you run a seperate fuel management system right? Do you have an A/F meter? Did opening up the runners on the low end lean you out at all? I think you run a wide band O2 up front as well. But how will removing the rod effect N/A stock engines? If I removed my rod and Nissan designed the low end to run off the smaller diameter runners, A/F would be based on that volume of air. Now this could concievebly double it at low RPM right? We now have lost torque, because we are running a leaner A/F ratio right? So the timing would retard until the A/F returns to stoic, most likely at around 5400rpm when the second runner would open.
So I guess it might be like the rustang people porting their heads too large and not keeping the air velocity up? Just kind of wondering how best to make this work. I will most likely put in an A/F this summer, I am working on a guage cluster for it. I do not get much highway, most of the stop and go stuff for me, so low end is best. The only time I went into triple digits was on the way to SIU, and have not done it on this car, it was an 83 RX-7 and I still had a few thousand RPM left, before I ran over the tire speed rating!

 

I don't really think this would matter. There is not a significant enough decrease or increase of air with the power valve removed. Also during normal open loop driving the car is constantly adjusting and your closed loop operation without the power valve would not affect the A/F to the point of concern

 

I have not done any A/F readings with the valve out yet, like Larry just said- when in closed loop the ECU keeps on adjusting stuff all the time, and my fuel maps on Emanage is setup for WOT only, so durring normal driving I'm still using ECUs maps for optimum power. After driving the car for a few days now I am noticing that the ECU has adjusted to the new found power, car keeps on pulln harder and harder every day. MAF sensor reads off lower voltages at lower RPMs- due to less air entering the engine- less power at low end. But I noticed quite a voltage increase on my PDA scanner at top end. I wish someone would do a dyno with the valve removed to see if there is a gain vs the valve in. I think its good for over 10WHP on top end, and raised rev limiter would be awesome to have at this point n time. Right now my VERY restrictive Cattman Ypipe is holding my top end. My cattman has been rewelded like 10 times now to keep it from falln apart, and I don't have my stock Ypipe. I do have a set of headers coming soon, so I will try to dyno tune it with headers n other stuff. I'm expecting around 240WHP with my mods. To me Torque isn't really a issue, I drive Hondas on daily basis and my car still has more low end than any Acura V6- 3.5L or 3.2L VTECs ( I am a Acura tech).

 

mike, I plotted dynos of my car vs. a de-k with the power valve removed. Its quite impressive. His graph actually crosses and passes mine a little before the original 5xxx VIAS opening (around 4500-4800 rpms)

however the car hits a wall afterwards and doesn't gain anymore. Some work on the IM will be needed or higher duration cams. The peak power is sustained very well, hence the feeling that the car keeps pulling

http://forums.maxima.org/showthread....e+removal+dyno

 

you wouldn't mind sharing that dyno chart with us would ya ??

 

actually, i found it... lemme host it and post it

mad2kmax (5spd, stock 16's, RT cat, y-pipe, full exhaust) no power valve
me (5spd, axis 18's, y-pipe, TS ecu) working VIAS

oh, btw... 4th gear runs

 

Looks like a nasty diff in TQ loss at around 3500-4K RPMs without the power valve in it. Is that all he had for mods ? I got quite alot more than that, I'm hopping to make way over 220WHP. I need to mess around with ignition timing and fuel maps on Emanage to bring the TQ back up a little bit. I know it will not bring ALL of it back, but I can't see myself driving a Honda like Nissan- low lowend torque. I wonder if his top end leveling off is caused by something like a restriced exhaust or intake... hmm should see mine soon.

 

I pulled the mods off his cardomain site. I'm fairly sure thats all he has. I believe the leveling off is due to the manifold + intake. Your car has been putting down more than most 5th gens i've seen anyways. If its choking, maybe he needs headers.

I plan for a modified IM, headers, tomei 264 cams, lightweight 18's, lightweight flywheel, and a TET prototype intake for high rpm power (battery relocation to trunk) then a TS reflash afterwards. I saw the same intake on a race prepped m3 at a local meet, although I may not opt for 4-5 diameter inch tubing like he did

i like how his max torque is AFTER 5k, it holds pretty well

 

I assume the intake is CF ? I would love to see pictures of it As far as Cams, I'm trying to source a set of cheap DE-K heads so I can get them ported and bigger valves installed, along with 270 deg Tomei cams. Headers are on their way again, flywheel is on the car, I don't wanna dyno with my heavy Blizzaks for now so I need to get a hold of my light 16" Z32 wheels for this dyno session. I won't be happy till I see 260WHP NA from a 3.0L, care less bout low end power really I need to talk to Crawford or Kinetix bout making us DE-K owners a cheap upper plenum which will make some awesome top end power- but once again not many Maxima owners will be interested and the deal will not happen. Its not a group deal on headlight bulbs or DDEs, so its out of the question for 90% of the people here.