V-AFC2 in a 1999ES (can spec) VQ35DE 2003



Things needed to get the mod done right: 95-99 maxima federal spec with VQ35 2002-2003 swapped and 95-99 ECU, S-AFC2 instructions and get the N6-C wiring for the maxima application 97-99 ECU, V-AFC2 with instructions any edition, FSM from 95-99 VQ30DE, 2002-2003 VQ35DE for ECU pin layout, 5 meters of 24 gauge electrical wire, iron solderer, shrinktube (1/4" or 1/8"), wire splicer.

The reason why going with the V-AFC2 is for the integrated RPM switch usually used for V-TEC changeover point, often forgotten and replaced with a RPM switch MSD 8969. Since we kept the 97-99 ECU, which is not designed to operate any VI opening and closing, we figured how to use the integrated RPM switch to activate the Vacuum solenoid for VI operation.

Let's get started:
-Disconnect battery and get it out of the car. Distance the two battery posts from each other.
-Get underneath the center console, passenger foot well side and remove the black plastic cover over the ECU. (it is clipped with plastic bolts that are just pushed in the holes, which 2 there is.)
-You will see a white plastic cover over the main ECU wiring connector, remove the 10mm bolt in its center to unlock the ECU from its pins and main connection (1 piece connector 124 pins)
-After removing the bolt, the fragile and very well clipped from the factory white plastic cover is retained by its 4 corners, remove it carefully. You will like to keep it.
-You will see a maze of wires, don't get intimidated and seek for the S-AFC2 instructions and get The N6-C for the VQ30DE application.
-After that, start seeking for the wires indicated in the scheme to get the color codes and pin layout right.
V-AFC2 procedures:
(solder all wires with silver soldering wire)
-Black wire: splice, solder the wires together 1 inch farther than the brown wire/farthest from the ECU.
-Brown wire:splice, solder the wires together 1 inch apart from the black /wire ECU side/ 1 inch from the ECU pin.
-Red wires(2):splice the IG power 1 inch apart each other and solder them together. Use the 2 red wires from the V-AFC2.
-White: CUT the MAF signal and connect the white wire far side of the ecu.
-Yellow:with the MAF signal cut, connect the yellow wire on the ecu side.
-Green: splice the Tach signal wire and solder the green wire
-Gray:splice the knock signal and solder together with the gray wire.
-Pink: this is the solution to get the VI activated. This is for the V-AFC2 vtec solenoid output signal. (RPM SWITCH). Connect the pink wire to a jumper wire and get to the VI vacuum solenoid actuator. Get that jumper wire to the top pin in the solenoid connector, solder. The second pin, the bottom one, get a jumper wire to the negative battery post, attach with o-ring connector to the bolt that goes through the battery post.
-Reconnect Ecu Connector and make sure the 10mm bolt is bolted all the way through.
-Reattach battery and don't forget to attach the jumper wire.
-Start the car and let it run until it is at normal temperature.
-Set the various fonctions to get the V-AFC2 read all the info right (TPS 100% gradually with pedal travel .4v to 4V in sensor check), (knock set idle HOT 650 RPM, 1650 RPM and 3650 RPM), (no of cylinder no. 1 with arrow pointing at the 2 o clock position, set HOTWIRE TYPE) maybe I forget something but it seems OK to me!!!

VI components checkup:
-Make sure all hoses vacuum hoses aren't clogged, choked and all connected the right way.
-One goes from the upper passenger nipple on the intake manifold to the center nipple on the vacuum tank.
-the second goes from the side front nipple on the vacuum tank to the left most vacuum nipple on the vacuum solenoid.
-The third goes from the right most vacuum nipple on the vacuum solenoid to the VI actuator upper ''hat'' part vacuum nipple.

VI opening/closing operations:
-After, set the V/T cont. to 3100 L-H and H-L at 3000RPM.
-Rev the engine and check if the actuator rod moves at approx. 3100RPM.
(3100RPM is the baseline RPM changeover point in the V-AFC2)

If so, repeat and check RPM and rod actuation quickness, it should move swiftly.
Go butt-dyno and try to get the best changeover point for you type of driving and type of mods you have on your ride. Don't forget to think about the fuel corrections you set to compensate for the upgraded air supply provided by the VI opening. Maybe some HP are left over without this thinking... The best thing to have is a wideband 02 sensor to monitor A/F ratio changes.

This thread has been written down on a sunday afternoon so, if all infos aren't exactly precise, pardon me!! Will be updated later on.

By VQ'ed and 97_roadrunner
__________________

 

good write up.

so far I am finding 4100 as a good cross over point. I previously had it set for 4600, and the change felt jerky, I felt the surge of power at 4600 when the manifold opened.

I'll only really know once I get on the dyno.

 

Why not set it to 3600 like it is from the factory? ...

 

Also, i hope you guys know that applying vacuum to the actuator actually closes the power valve.

 

I noticed a large number (including myself) have been using the wrong word when it comes to the manifold. I took apart my IM for the 3.5 and its actually "open" naturally, and at the given point, the valve closes.

 

Exactly. With that said, how can the V-AFCII possibly control the VI?

 

wire up the VTec output to the sensor that is located on the Manifold (3.5 manifold) and with the canister and vacuum lines properly routed, once the VAFC send the 12v signal to the sensor, it will close the valve

 

I understand that much, but the power valve is closed from the factory from 1800-3600 RPM. You'd need a window switch for that. Even you kept the power valve closed from idle to 3600, could the V-AFC II apply 12v to the solenoid at RPM's that low?

 

the VAFC could open it at any given rpm, but its switching to the second 12 point map when it crosses over, so gotta plan it out well.

it can only close the valve so, sadly there is no closing, then opening, then closing again.

 

That right!
The V-afc2 only activate the 3.5 VI once, just like an 00vi.
Unfortunately it is not as good as the stock setting, but it's far better than running only on the long runners
After a good "Butt-Dyno" the switch over point was set back to 3600rpm.

 

The problem isn't the fact that the V-AFC II can only activate the VI once but that when it activates it's actually closing the VI.

 

By that, do you mean the VI is on short runners when vacuum in not applied?
I tought the VQ35 VI was on the long runners by default...
The 2002 VQ35 fsm show that the selenoid is powered when ignition key is on the "ON" position. So when the engine is fired-up and create vacuum, the VI should be switched on the short runners at idle. Then the 2002 ecu activate the long runners between 1800~3600rpm by closing the vacuum selenoid. Correct us (VQ'ed and I) if we are wrong, because we are realy involved into it.
Thank twice nismology...

 

Yes. When vacuum is not applied the power valve is in the open position. So when the V-AFC II activates the solenoid and vacuum is applied to the actuator it closes the power valve. I don't see how anything other than a window switch can operate this VI properly.

 

nothing besides a window switch/vafc/rpm switch will close the valve.

 

I didn't think you could set a "high RPM limit" with a V-AFC II/RPM switch. You can tell it where to start but you can't tell it where to stop as far as i know.

 

You can with the VAFC in particular, you can tell it to close the valve at say 3800 rpms, at that time to changes over to the 2nd 12 point map, you can program it to switch back to the first map, for example set it at 3700.

so at 3800 when rpms are rising the valve closes, and when rpms descend below 3700, the valve opens back up.

 

Why would you want the valve to close at 3700 RPM? It's supposed to OPEN around there.
That's the exact opposite of what you want to happen. The valve should open around 3600 RPM, but you can't set an upper RPM limit while the RPM's are rising with a V-AFC II. I don't see why it would have that feature either. Why would a honda owner ever want to engage VTEC only to turn it off later in the RPM range?

 

Let me summarize my position:

1. The power valve is open by default.

2. Applying vacuum to the actuator by energizing the solenoid valve via the V-AFC II CLOSES the power valve.

3. The V-AFC II does not have the ability to activate the VI until 3600 RPM and then disengage, opening the power valve.

4. A window switch set to activate between 1800-3600 RPM would be ideal. Actually, it's the only viable option out there, IMO.

 

correct
correct
The VAFC can activate an any rpm, but where it is set to activate is the window for that map.

Example if you close it at 1800 rpms, your first 12 point map would need to be between 0 -1800 rpms, so very limiting. If you set a higher rpm say 3800, your first map can have 12 turning points between 0 -3800 rpm.

So basically we have to plan where it will close the valve, and also plan for wide enough range for the 12 points we have, before it crosses over to the second 12 point map.

The VAFC can close the valve once when rpms are rising, and open it once when rpms are decending

I believe some had double tapped the rpm line on the ecu, and there simply wasn’t enough power going thru to feed the VAFC they had and the rpm switch. Other suggestions were made to try to solve the problem but I believe the poster was content with just the VAFC. But what your suggesting would be the ideal solution

 

Exactly, what we wanted was at least 1 stage opening/closing instead of nothing at all... Imagine if you have all the materiel to get it opened but wasn't able to use it. My buddy have the swap done for 2 years now and was still left with an unoperative VI. After the V-afc2 installation, the VI moves and still being tested to have the best out of it. After testing, we gonna post results, don't forget over here it's -20degrees outside and icy... not like +25degrees t-shirt and shades, testing all day.

 

Then it can't really control the VI.

 

I don't think you guys understand what im saying. The V-AFC II can control the VI, but it will be the opposite of what you want. It will close it when it should be open, and open it when you should be closed. With a regular type of VI that is closed by default, you can set it to open at ANY rpm since there is no upper RPM limit. You just let it ride to fuel cut. With this type of VI that is open by default, you need an RPM switch that has both a lower and upper RPM limit (aka window switch). If you can't shut an RPM switch off at 3600 RPM then it can't work with this type of VI.

 

OK, let me get this straight, If the VI opened and after the set RPM it closes, we would still have a changeover in the intake. Which fonction the converse way it's suppose to be. Is there anyone who tried this way, out there. Is there anybody who can tell us that's a bad way to extract power if ANYBODY haven't tried it wet??? I know this is not the way the nissan engineers intended the VI to work but If there is any performance gains, you will all know from us.Too bad, if we mistook but, at least, we work on a weekly basis to upgrade our cars during winter at the same time all the other members over here eats fries and chips on their couch thinking about summer...

 

I see what your saying. I havent heard or seen anyone install a window switch on to control the VI. Most just use an rpm switch or vafcII, so in a sense we arent controlling the VI like its mean to be.

 

Why do you not just get a cheap 12 vdc automotive relay with a set of forrm C contacts?

Wire the solenoid through the normally closed contact to an ignition on switched power source. Wire the coil between your vtec output and ground.

When the rpms hit your switchover point, the relay energizes, the normally closed contacts open taking power away from the VIAS solenoid and the power valve opens.

It is not ideal, as the valve would remain closed from idle to your switchover point, but it is the best you can do without a more advanced controller.

 

You can make the VI work, but it would be in direct contradiction of the way it was designed to work.

 

A window switch set to energize the VIAS solenoid between 1800-3600 RPM would work just fine, no?

 

Well of course it would. That is what I meant by a more advanced controller.

A relay is $5. Hell I will send them one if they pay the postage. How much is a window switch?

 

Ah i see.
$90+...

 

I've figured it out!!!
Tough, but... nothing that, good old GOOP, cant fix!

You set the switch-over point at 3000rpm, as it's the
lowest point the V-afc2 can activate the selenoid.
You glue with Goop, a micro-switch on a custom metal bracket
on the TB, so the micro-switch is activated only in WOT.
(Just like a drop resistor mod.)
You wire the micro-switch, on the normaly closed taps,
between the selenoir and the V-afc2.

This would make the VI work like this:

Idle~3000rpm = Short runners
(V-afc2 activate the VI at 3000rpm)
3000~4000rpm = Long runners(if TPS< 99% opening)
and
4000~6500rpm = Short runners (If in WOT, the micro-switch cut power to the
selenoid, so the VI open again!!!!)
or
3000~6500rpm = Long runners (Si TPS< 99% opening)



Total cost:
micro-switch 1$
bracket 0.39$
glue 1$
wires and solder 1$

less than 4.00$

It's so simple, it'a almost indescent...


We will try it saturday and we will tell you guys how
it's working out for us.

 

I applaud the ingenuity () but i don't think this will be much different than keeping the VI open full-time. 1k RPM goes by pretty quickly at WOT and all the power valve would be doing is fluttering in the lower gears. Let us know how it feels though.

 

Thanks!! Can't wait to do it... Geez..5 days to wait!!!

maxpower96 (the owner on the car) had already done a real Dyno test and he told us, the graph shoed a huge torque dip between 3000 and 5000rpm... should we activate the long runners til' 5000rpm then??? Is this due to his intake and exhaust set-up?(Short ram, 03 headers, 4th gen y-pipe, b-pipe with eom muffler)

THANK TWICE, your are the up-north mentor...

 

Great team up guys!! thanks you guys down south for helping us and keep track of our ideas. We knew over here that, some day, you would help us out!
Gonna keep you informed of the results. Dynoing in february for me and maxpower96. (giving me time to purchase my wbo2 sensor and display gauge)

 

If the VAFC applies a ground when off then you can just to some simple relay wireing to make it send 12v below the rpm switch over, and then when the switch over happens, lets say 3600, you can make the relay turn off thus no power to the vi.

 

1800 - 3600 is for stock A33B...w/VTC's.

Check this link for dynos w/ no VTC and various opening/closing settings.
http://forums.maxima.org/showthread.php?t=475915

 

^^ Thanks for bringing that scenario up. I always wanted to comment on that but never got around to it. To me, it looks like he got it backwards too. He must not know that the power valve is open by default. I seriously doubt his findings would be in direct contradiction to nissan's design parameters. VTC or not, a IM's general characteristics are its characterics.


The green curve is characteristic of a closed VI, strong low end, but the midrange is lacking.

The red curve is characteristic of an open VI, low end lacking, but strong mid-range.

What happens to the red curve up top, though, is just plain weird to me. Never seen a modified 3.5 dyno where the torque dropped off that quickly.

 

the next weekend will be the first try on what you mention this week, we take all the ideas and gonna check what is most appropriate to get it work the right way. And yes, nismology, we understand the way it works actually isn't the best way. Gonna take your advices and post results afterward. thanks!!

 

You are right nismololgy, I incorrectly stated the open/closed power valve positions in that post. I do understand that the non-vacuum position (RED in my dyno) is in fact open and that the green is closed. While I still had that A33 IM, I used an RPM switch for a single point activation at 5800rpm to take advantage of my 7,000rpm JWT redline.

The drastic torque drop off could have been associated with my restricting VQ30 stock exhaust manifold. I then installed my 2.5" true dual setup, but never got around to dynoing to see the high-end change in power.

 

Keep up posted, can't wait to see the outcome. For better 1/4 mile times would u set the rpm swtich to 3600 or 4000.

 

Any RPM setting for any car needs to be dyno & track 'tuned' for each car's specific power curve.