stock boost selenoid

[BigPar]

Is it essential to run the stock boost selenoid with the RB25DET? I haven't been running it since my swap, and my two friends were having an argument of what it would do if hooked up. So with a little expirimentation we hooked it up to see if it would keep the boost at stock and not allow it to creep, since im running no exhaust, or atleast limit the creeping. I was originally hitting about 9-10psi and having cutting in and out problems.

So we hooked up the selenoid, and I went out and did a pull. I was hitting 18-20psi and it felt REALLY good. No hesitations or cutting in and out or falling on its face. So after calling and telling him what it did he was like oh ****, lines are on backwards, bring it back. So I bring it back, we switch the vacum lines, and I go out again. I did a pull and hit 20psi again and still no cutting out. So I get back and we decide to just leave the selenoid plugged into the harness with no vacum lines on it. That maybe the ecu just needs to see it plugged in.

We also realized that the vacum tee we put in was kind of small and may have been causing the high boost. We put in a larger vacum connection tube and put it back into the manifold, leaving the selenoid plugged in the harness, just no vacum lines on the selenoid. I did a pull and it only hit 6.5-7psi and had crazy hesitation stuttering cutting in and out. I couldn't boost over 7psi. We decided after we got where we were going to just put the vacum lines back on the selenoid, this time using the larger vacum Tee. In trying one more pull I blew the coupler off the side of the intercooler, which is a 4ply coupler with T bolt clamp. I was amazed cuz I usually blow off the ****ty no ply silicon coupler i have on it. So id didn't get to really see what it did that last time and am going to see today.

But overall, is the selenoid suppose to be used or atleast plugged in?

[Kansei240sx]

screw that peice of crap. I got one with my motorset but never used the thing, Just run a vacuum line from a boost source to your wastegate.

[Joe]

screw that peice of crap. I got one with my motorset but never used the thing, Just run a vacuum line from a boost source to your wastegate.

that will work

but your ~3psi low. the boost solenoid runs the rb25 at 8psi rather than 5.5 psi (wstegate spring). i ran without the solenoid for a bit but thats less boost than out of the factory so i quickly upped it.

[Kansei240sx]

Hrm, that sucks Kamin, I never use the boost solenoid, and i had 8psi all the time, and then anything past 5200 rpms VTC point, i'd hit 10psi and it was stable.

[themadscientist]

How about a real boost controller guys? They more OE **** I rip out the faster the car goes, lose that dumb thing already (automakers have entire departments dedicated to designing needlessly complex solutions to simple problems I suspect) and get simple reliable boost control. ie; adjustable wastegate or a boost controller.

[Joe]

Kansei...your saying you had the wastegate hooked directly to a boost source with no boost slenoid and you were hitting 10psi?

That sound strange to anyone else?

[Kansei240sx]

Doesnt sound weird to me, it only went to 10psi after 5200 and since the timing is being advanced along with having a exhuast, short FMIC piping route, doesnt sound too off to me.

[WilYawn]

Makes sense to me. If you have an adjustable actuator you dont need the solenoid. Just hook it it up to a boost soure (preferrably as close to the turbo as possible) and adjust the actuator arm to your desired level of boost.

BTW: First time poster, Skyline owner from Sweden

[rustbucket]

Hrm, that sucks Kamin, I never use the boost solenoid, and i had 8psi all the time, and then anything past 5200 rpms VTC point, i'd hit 10psi and it was stable.

Mine was the same way before I got the hks evc 4.

[300Plus]

I was running the boost source right to the wastegate and was hitting the same (8psi, then 10psi in high rev) but I later plugged in the stock boost solenoid and left the vac lines off. having the solenoid plugged in seems to smooth everything out.

so your stock turbo held out to 20psi? did you keep running it at 20psi? that would def lean you out.

[BigPar]

Did a pull today on the way home from work. Didn't want to mess with it on the way there and not make it on time, or at all, LOL. So basically I have the selenoid plugged into harness, wastegate vacuum line into the top nipple on the selenoid, and vacuum line from bottom nipple to the intake manifold. I hit 22psi really quick, and at only 75% throttle at most. I eased into it and backed out once i saw it going up in the teens real fast. The car didn't seem abnormally faster this time, or even when i took it to just 13psi with 50% or less throttle to get it there. It seemed faster and pulled harder the other night when i hit around 18-20psi.

I have an AEM Tru boost gauge/controller, but I just don't have the controller module hooked up, just reading boost now. I was waiting to install the controller part after i got my nismo fpr put on, but now thats on. I'm going to get rid of the selenoid tonight and put on the controller module, and see what it does then.

Although when it was hitting 10-22psi those times, it never cut out or hesitated. But the old way of no selenoid at all, it would cut in and out and fall on it's face at 9-10psi. And selenoid plugged into harness and no vacuum lines attached would have it only hit 6-7psi and cut in and out real bad like hitting a boost limiter/fuel cut.

[themadscientist]

BTW: First time poster, Skyline owner from Sweden

Welcome.