HOW TO: RB25DET High Boost mode with standard solenoid

[Reaper]

Taken from paulr33 @ skylinesaustralia.comhttp://www.skylinesaustralia.c...42895

HOW TO: RB25DET High Boost mode with standard solenoid

Intended Audience: Stock RB25DET ownersTechnical Level: Very EasyDuration: 5 minutesEffort: EasyResult: Fairly Good

!!!Caution/Achtung/Attenzione!!!Follow this guide at your own risk. You have been warned. We are not responsible for any actions you take. The instructions contained herein are only a guide and should be done with caution, If you doubt see your local mechanic. If you are unsure or are not confident don't do it.

Background:

As you all know the standard R33 RB25DET boost solenoid (value controller) is 5psi until rpm is greater than 4500rpm and then its 7-8psi. Continue reading if you wish to always be in high mode (7-8psi). If you have an aftermarket boost controller then you can stop reading now.

The standard solenoid has two wires running two it, one is constant power which is shared with the AAC value and some other components (see wiring diagram) the other is a ground signal. The ground signal (black wire) is run to the ECU. This wire is grounded when rpm is greater than 4500rpm by the factory ECU. Basically if you give the wire a constant ground instead of the ECU's above 4500rpm ground it will always be open, thus allowing it to be in high mode aka 7-8psi.

The mod:

Cut the black wire and run it to your own ground on the car body somewhere. Find a local bolt/nut or metal chassis component and attach a lead wire to it, then run this lead wire the black wire on the standard solenoid. For testing you could run this to the suspension tower, is has a huge bolt/thread on top of it. The other end of the two wires (black and white) should run to the factory harness plug (black odd looking plug), which can be simply taped up so it goes nowhere.

Be sure not to the modify the white one, as it's power for the solenoid.

See new-wiring.jpg for how it should look

Basically the black wire goes to your new ground, the white wire doesn't change. Make sure you tape up the loose end of the black wire out of the plug and don't leave it dangling around. Now to test

Test:

Start up your car, make sure you don't have any alarms or warning lights etc.. Safety is important!. Instead of your car going into 7-8psi above 4500rpm it will be in this mode all the time, this means when you take off in first youll be limited to 7psi instead of 5 and thus applies for all driving thereafter. Take it for a quick spin and see the difference. You'll notice first is whole different feeling to it and each gear thereafter seems to have more stick about it. Your top end power output will not be changed, ie if you made 140rwkw and you've done this mode it will still be 140rwkw it's just the curve will be sharper as you'll be on more boost quicker

Tips:

If you don't notice any different then you've either done the wrong wire or the ground is strong enough. Be sure to pick a strong ground and make sure its secured properly. You can get gold washer clips which will hold a wire and provide a good ground for use on a nut (see the yellow thing in new-wiring.jpg)

If in doubt you can simply unplug the black factory harness plug and your controller will be in closed mode which is 5psi all the time. With only a power signal the solenoid doesn't function and thus it will always be in "closed" mode which is 5psi

Questions?

How does the solenoid work?The stock solenoid works like this, with power and ground it will be in "open" mode and let through a maximum of 7-8psi. With only power it will be in "closed" mode and will only allow through about 5psi. The ECU makes it go into "open" mode by giving the black wire ground signal which makes the circuit complete. All you are doing by "adjusting" the black wire is making the circuit complete all the time.

What will happen above 4500rpm now that I've done this mod?The ECU will still ground the wire above 4500rpm but nothing will happen. As long as the black wire is taped up you will be fine. Of course if you are creative you could run this wire to something else and it will be turned on when rpm is greater than 4500rpm. Crap like turn on the water spray kit for the intercooler, flash a light, do some other crap

I've broken something, can I reverse what I have done?Should you do some damage or have broken stuff you can get a stock boost solenoid from the for sale section of the forums for like $50 tops, as its fairly useless when you have an aftermarket boost controller. The standard wiring is fairly simple, one is ground one is power. You can't have a circuit without both. See wiring diagram if you are unsure or doubtful.

Have fun and enjoy

[s14kouki]

It'll give it a nice lil kick, but to really feel a difference a boost controller is a must.

[blurrbosi]

haha...sweet

[Reaper]

true, i just read it over there and thought some people who couldn't afford a controller right away could do this while they were waiting.