Is the butterfly valve in the 3.5 intake manifold supposed to be open or closed from idle to ~3,600 RPM? How about above that point? The Nissan dealer (and a few org'ers) say closed at low RPM's and open above 3,600...others say open from idle to 3,600 and closed above 3,600 (to separate the intake runners b/w both sets of cylinders). OK guys...which way is it supposed to be? Thx...

 

closed at low rpm's, and open at high.

 

I was sent this link yesterday: http://forums.maxima.org/showthread....ght=00VI+A%2FF. In about the 4th paragraph (begins with "What's the difference..."), it discusses the 5.5 gen IM and how the butterfly valve is OPEN at lower RPM's and CLOSED at higher (to separate the IM halves). This contradicts what you've written, Tavarish...any thoughts? Thanks very much for the reply.

 

Tavarish is correct. Read this.

 

That's what i was trying to explain to you via PM. The ECU activates the power valve at >3600 RPM by CUTTING the vacuum signal. I know what Jime just posted shows the opposite (that the power valve is activated by applying vacuum) but i'm taking my info from a revised version of the 2002 FSM. Either way, the important thing is that the power valve is closed at low RPM and opened after 3600 RPM.

 

I just visited the local Nissan dealer to see, with my own eyes, how it works. I had the salesperson rev an '03 Max to 5K. The valve begins (at idle) open until ~1,700, at which point it closes and remains so until ~3,700. It then opens again and remains that way until (at least) 5K. So...I'll go out and change the configuration on my car. One last question...what size inline fuse would be appropriate in the direct 12V run b/w my battery and the VIAS solenoid?

 

If you read the bottom caption of the page it also says the valve is only closed between 1800-3600 which means it must be open above 3600 and below 1800. So in reality it is open at low RPM according to the FSM.

 

VERY helpful...I was especially confused after reading the link I provided and by then comparing it to what I was being told. No offense intended, guys...just want to make sure all is done correctly.

 

And in response to that link you posted... the reason that people probably thought that the power valve is OPEN at low rpm is because they most likely took off the power valve cover with the motor off to take a look and without a vacuum signal since the motor is off, it stayed open. They saw that and assumed it was like that with the motor on as well. This is not that case since as soon as you turn the car on, vacuum is applied to it and the valve closes until the motor warms up. Hope that makes sense...

 

Jime...so it's difficult/impossible to emulate the stock setup without a "full swap" (as I have only one on and off RPM setting on the switch). I suppose I'll just set it for "closed" from idle to 3,600 and "open" from that point on up to redline. It seems as though that's the best I can do, doesn't it?

 

Actually Nismology, I dont think it is closed as soon as you start the car (an '02 + car, that is, based on my visit to the dealer and using a cold engine). It appears to be open until around 1,800 or so, then it closes until just under 4,000, at which point it opens once again.

 

You can get a window switch to emulate the stock ECU. You'd have to set it to OFF (idle-1800 RPM) - ON (1800-3600 RPM) - OFF (3600-redline).

 

You can do it with an EU but like you say most windows switches just allow an on-off or off-on. I do think the MSD 8969 will do it but I can't confirm it. Regardless I don't think being open below 1800 will make any kind of a difference like above 3600 will.

 

Well i was just going by what the FSM said about checking the VIAS control solenoid valve. It says you should check the valve with an "warm engine" condition. I guess ultimately it doesn't matter whether the engine is cold or not.

 

Couldn't you just set one to "ON" from 1800-3600 RPM and everything else would be "OFF"?

 

I have a dyno from ~ 3500 RPM(auto) comparing 2 runs where I d/c'd the vac canister, and on the other run left everything as is (stock)

This can't speak for 1800 -3600, but ... IMO, this isn't a big deal.

Best idea, is hit the dyno... and get your ideal set-point from there...

This will be optimal since you do not have VTC's..

 

I said this too in his other thread. Guess i know nothing...

 

Yes you did sday that. 1+1

 

Either way, if you really want to emulate the 2k2 ECU, you should get a window switch and set it for on from 1800-3600 RPM. This will work since applying vacuum closes the valve.

 

I'd rather spend my time doing better things rather than trying to emulate the stock ECU for this particualr aspect.

I would rather be working on a custom VTC 'box'.. rather than this VIAS BS.

 

Thanks 4 all the help guys...the "Org" is such a great resource! One last question, though...what size inline fuse would be appropriate in the direct 12V run b/w my battery and the VIAS solenoid?

 

So are you going with a window switch or RPM switch? In any event, just for clarity's sake, you need something that will turn OFF the vacuum signal after 3600 RPM.

 

I must have been unclear. I've already installed the MSD (8969?)...the digital window switch. Right now, it's set so that the butterfly valve is closed from idle to 3,600 and open from then up to redline. Sound good? I was considering your idea about open from idle to 1,800, closed from there to 3,600 and open from 3,600 up...I'm just not sure if that would really make any noticeable difference. I think I may leave it as-is for now.

 

Now...about that fuse size???

 

Well i understood that you wanted to have it open up at 3600. But what im saying is that in order to open the power valve the solenoid shouldn't be getting a signal. In other words, the window switch should be set to be ON from idle to 3600 RPM. That's what i was trying to say. If you already picked up on that, disregard this post. lol

 

You'd think that was your sig