Vct Setup On Rb25det

[Harry50601]

Hi guys.

Awhile ago I completed a engine conversion on my r32,using r33 rb25det series 1 motor. The way I did it was using factory r32 rb25de loom with r33 rb25det injector plugs and matched up with r33 rb25det ecu. Since r32 does not have vct therefore there's no plugs/pin outs in the loom to the ecu. I've since left the vct plug vacant. But I would like to know whether I could just somehow earth them so vct's constant on.

[PM-R33]

You don't want it constantly on because you will have shit top end power. You need to switch it off up top so you get your top end power.

You can get it working easily since you have an RB25 ECU. Just run additonal wires from the VCT solenoid to the ECU. Get a pinout diagram and hoop up the earth and power. From memory the power is a constant and the ECU switches the earth via rpm. The pinout is #113 on the ECU for the ground.

Edited January 21, 2010 by PM-R33

[GTScotT]

what would be even better is work out what pin it is on the ecu and run a wire thru ur dash wouldnt you say

EDIT: Beat me to it PM-R33!!

[Harry50601]

cheers boys..but how exactly do I do that, I no longer have the factory r33 loom, any other way I could hook it up from the connector?

[PM-R33]

The solenoid will have two prongs on it, one for the positive and one for the negative. The loom normally has a connector going to the solenoid which clips in, just solder the wires directly onto the solenoid prongs.

Or track down a connector plug and just re-attach it to some wires. I'm sure people that have got rid of their VCT for some big cams would have a connector plug lying around.

Edited January 21, 2010 by PM-R33

[Harry50601]

The solenoid will have two prongs on it, one for the positive and one for the negative. The loom normally has a connector going to the solenoid which clips in, just solder the wires directly onto the solenoid prongs.

Or track down a connector plug and just re-attach it to some wires. I'm sure people that have got rid of their VCT for some big cams would have a connector plug lying around.

sorry to be such a noob..so earth just go on to any earthing point of the chassis and constant to the pin out on the ecu? forgot to say power fc is gonna be replacing the factory ecu in a few weeks time, still ok to just wire the vct solenoid to the ecu this way?

[GTScotT]

find a plug for your VCT solenoid, then work out which pin goes to what on the ecu. solder 2 wires to the plug you bought, and run them to the appropriate pins on the ecu.

should be really easy. from what PM-R33 is saying you connect 12v from batter to one wire to the solenoid and run the other to pin 113 on the ecu. simple simple simple.

BUT make sure you double check EVERYTHING as in how its wired and what pins what via a wiring diagram BEFORE you proceed.

GL

[PM-R33]

Sorry Harry i think you missunderstood me.

The earth will go to the ECU pin out #113 (Get yourself a pin out diagram and double check this). The power im not sure where it goes exactly from factory, most likely onto another pin on the ECU but i'm not sure which one off the top of my head. You could probably just hook it up onto any 12V ignition source.

Yes it will be fine to wire it this way as the Power FC uses the VCT also.

Like i said the earth is what switches the VCT on and off, so this goes to the ECU pin out #113 and the power source should just be a 12V ignition source.

Hopefully some one else can verify this.

Edited January 21, 2010 by PM-R33

[Harry50601]

Sorry Harry i think you missunderstood me.

The earth will go to the ECU pin out #113 (Get yourself a pin out diagram and double check this). The power im not sure where it goes exactly from factory, most likely onto another pin on the ECU but i'm not sure which one off the top of my head. You could probably just hook it up onto any 12V ignition source.

Yes it will be fine to wire it this way as the Power FC uses the VCT also.

Like i said the earth is what switches the VCT on and off, so this goes to the ECU pin out #113 and the power source should just be a 12V ignition source.

Hopefully some one else can verify this.

Oh I get you now, so If i wanted to i could simply run 12v constant and earth and a simple on/off switch to control vct? and#113 pin is correct.

[PM-R33]

In essence yes, however with it constantly off, you will get shit low down power on the stock cams. With it constantly on, you will get shit top end power. So really a switch controlled by you wont work properly.

[The Dan]

Do not put it on a switch, that is stupid.

Do EXACTLY what PM-R33 has said to do. If you don't understand, read his posts again. He has explained it very clearly.

Also...it is a solenoid so it doesn't matter which pin goes to what, just make sure one of them gets a 12v from the battery and the other wire goes to 113 on the ECU....simple

[paulr33]

yeah ive tried Rb25 with VCT off and it runs sluggish like a cop

having a switch or perm off or perm on is stupid as others have said

wire it as per normal install, on the powerfc with datalogit, you can adjust the switch on/off RPM point (but not disable it)

[Harry50601]

yeah ive tried Rb25 with VCT off and it runs sluggish like a cop

having a switch or perm off or perm on is stupid as others have said

wire it as per normal install, on the powerfc with datalogit, you can adjust the switch on/off RPM point (but not disable it)

I had a look at the solenoid connectors last night, one prone is bigger than the other but as Elite Racing stated doesn't matter which way it goes. I'll try do it tonight, one goes on to the 12v + terminal on the battery which eye connector and other wire just route it with the loom through the firewall into pin#113 on the ecu? What sort of connector do i need to use for connecting to ecu or the factory plugs already got the provision to take a wire?

Thanks heaps guys, I'm one more step closer to get the car running as it should be

[Don Dada]

Do not put one pin of the solenoid directly to the batt., connect it to a switched ign source.

Not sure about if the rb25de harness already has a wire out for the nvcs, if it has one that means it will already be some where in the engine comp. if not it will just be blank so u need the pin out to verify.

If its blank you can get a similar nissan harness and surgically remove a pin/wire from it and place it in your harness.

[PM-R33]

Yeah don't do it straight to the battery, use a 12V igniton source as i said. You have to run one wire inside the car so you may aswell just run them both into the car. Then find a 12V ignition wire on the ECU and splice it into that.

[Harry50601]

Yeah don't do it straight to the battery, use a 12V igniton source as i said. You have to run one wire inside the car so you may aswell just run them both into the car. Then find a 12V ignition wire on the ECU and splice it into that.

sort of got it wired up, 2 wires coming out the solenoid. Run through fire wall, one wire goes to 12v constant (cigarette lighter 12v) and one go straight into left bottom 5th socket , ie pin #113.

I was being experimental, so I wired up to a constant earth, the turbo whistle much louder but lack of power from 5k rpm to redline as you said, and also I noticed when I am slowing down to about 30 odd ks in 3rd or 2nd gear it knocks (I guess it's because of the extra air=lean?). So I swapped around the wiring to the ecu, runs fine now but I shouldn't be expecting a VTEC kick sorta thing right?

[Don Dada]

I experimented with this on the stock ecu using a msd adjustable window switch which allows u to set what ever rpm u want it to switch on and off at and i must say the seat of the pants gain was verrrry minimal.

The boost did seem to come in slightly earlier and ramp up a little quicker but i think similar gains could be made with a good tune in this area of the map and leaving the nvcs disconnected totally

I have a dyno sheet somewhere around.....i'll see if i can find it.

[XRATED]

What kind of amperage dose the coil draw? (Or what size wire goes to-from the coil?)

2 or 3 Amps?

Cheers

Justin

[Simon-S14]

XRATED: stuff all. wouldnt even be a single amp.

to the OP: ffs man, if its too hard get someone who knows what they are doing to do it for you. i realised you worked it out in the end and you played around with leaving it on, but it took you 20 ppl to tell you the same thing before you figured it out

[radium69]

Sorry to bump an old post, but I find this topic has very valueable information regarding the VCT system nissan implemented.

I have a few questions remaining for my own R33 GTS-4 +T with RB25DET ECU.

The VCT system on my R33 is stock and in use.

However, since changing boost pressure, 0,45bar -> 0,75 bar I notice a flat spot starting at 5000 till 6200RPM.

This seems to be caused by the VCT not suited for higher boost pressure. Turning it off wil make it like a pig (as said in this topic)

But like Paul said, i want it switched off in high RPM, to see if the flat spot will dissapear.

How can I do this?

- Cut Original positive lead from ECU and tape it?

- Then, fit a new wire to sensor, connected to ignition switched 12V source?

I understand the reason to go for an ignition switched 12V source, but is it only because of battery drain?

Thanks for all the information so far!

Edited January 11, 2016 by radium69