Variable Intake Runners (QR25DE) - Nissan Sentra Forum - B15, B16 and B17 Sentra Forums
 
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post #1 of 12 Old 04-23-2002, 08:53 PM Thread Starter
ezcheese15
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Variable Intake Runners (QR25DE)

Has anybody tried modifiying the VIAS yet? I've been looking at the wiring diagrams. I'm wondering if I can make a control box to adjust where the runners switch, instead of the stock 5000 rpm switchover point. I'm thinking there may be more power to be gained.

Looking at the wiring diagrams, the VIAS control box has one wire fed into it from the ECU. At RPMs under 5000 rpm, the wire sends battery voltage to teh VIAS. This causes to the VIAS to block of the vacuum signal to the power actuator, and the shorter runners are closed. At rpms above 5000 rpm, the ecu sends a voltage signal to the VIAS of less than 1 V. This causes the VIAS to open, creating vacuum to the power actuator, thus switching the intake runners to the shorter runners.

Is it possible to make a control box where I can adjust the switchover point? I figure I can have an incoming signal from the tach, which is measured in voltage. Another wire coming in would be battery power. A third wire coming in could be the low voltage signal, (probably tap into the upper O2 sensor since it is always between 0 and 1 V). Coming out of the box would be one wire, that would go to the VIAS. The box would be a switch with a variable switch point on it. The switch point would simply be adjusting the voltage at which it switches (tach wire). It would send either the signal from the battery voltage, or the O2 voltage depending on the rpm.

Does this seem feasible? I'd like to hear of opinions on this. Or if somebody has succesfully done this, how you did it.

Torry
08 G37
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post #2 of 12 Old 04-24-2002, 07:40 AM
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It should be able to be done with a little electronic wizadry I will check the FSM at home tonight a look up that section. I'm sure some kind of workup with a pot would work good.
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post #3 of 12 Old 04-24-2002, 07:55 AM
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It would be sweet if someone could rig a switch you could flip when ya want the extra power... now all we need is the turbo damnit!!!

Ebony 2002 SE-R Spec-V Built: 04/10/01
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post #4 of 12 Old 04-24-2002, 09:08 AM
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I have a little button that I push when I want extra power...it's on my gearshift lever....it's the overdrive on/off button

seriously...overdrive is a pain in the a$$...I'll be going 30mph and I'll hit the gas to pass someone or something and my car will just go grrrrr like it's telling me "I'm in overdrive stupid!"

Last edited by 02.blue.seR.mia; 04-24-2002 at 09:11 AM.
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post #5 of 12 Old 04-24-2002, 09:11 AM
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Talking

Quote:
Originally posted by 02.blue.seR.mia
I have a little button that I push when I want extra power...it's on my gearshift lever....it's the overdrive on/off button
exactly!! that's my favorite part about the stock auto ser!!

2K2 SE-R, PR CAI
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post #6 of 12 Old 04-24-2002, 09:19 AM
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Even with overdrive one, when you step on it, it should downshift for more power.

2005 Maxima SE
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post #7 of 12 Old 04-24-2002, 10:45 AM Thread Starter
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Quote:
Originally posted by vbspecv
It should be able to be done with a little electronic wizadry I will check the FSM at home tonight a look up that section. I'm sure some kind of workup with a pot would work good.
If you want to find it faster.....

The VIAS system is located on pages EC-1768 through EC-1776, and the tach signal is located on page DI-18.

Torry
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post #8 of 12 Old 04-24-2002, 11:04 AM
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you should be able to acheive 1.4 gigawatts at 4,000 rpm's if you add a flux capacitor.
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post #9 of 12 Old 04-24-2002, 11:08 AM
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1.21[GW]!!!!

'02 Vibrant Blue SE-R - 5Spd, K&N Drop-In
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post #10 of 12 Old 04-24-2002, 01:41 PM
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That would be interesting to see. Not that the engineers hadn't already determined the optimal point of switchover =) but that would be interesting to swith the intake runners at different rmps to see a result... maybe that's one step in managing a supercharger or torbo setup... long runners under light/no boots, and the shorter runners at half to 3/4 and maybe both open (somehow?) on WOT. Much more airflow force on the shorter runners.

Just expanding onthe thoughts.

Last edited by RykrosGT; 04-24-2002 at 01:45 PM.
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post #11 of 12 Old 04-24-2002, 01:59 PM
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Well the engineers at Nissan's first job was probably fuel economy not performance. If it was performance the engine would be pumping out 250hp
Also I am pretty sure the opening of the intake runner is an all or nothing thing. So I doubt 3/4's would be possible.
If someone figures out how to do it, I will dyno test it

Lee
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post #12 of 12 Old 04-24-2002, 04:53 PM Thread Starter
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I'm not trying to vary how much they are open. I want to vary the *point* at which they open (instead of 5k rpm, select something lower).

Torry
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