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How to disable stock rb25det boost solenoid?

Cake

By Cake,
in Engines & Forced Induction

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Cake Mentor

Cake

Posted
Posted

Ok I want to run the minimum possible boost, without the factory 2-stage boost control solenoid raising the pressure by 2psi over 4800rpm. I will be fitting an EBC soon anyway, but this still needs to be done first.

If you look at this diagram (bottom pic only), http://forums.skylinesdownunder.co.nz/atta...s=&postid=97198. I set it up identically, to that, except i did not bother blocking off the solenoid outlets (as shown in red on the diagram). The hose drawn in blue was connected directly into the wastegate actuator line as shown. Now this caused my car to run extremely weird. I have heard of leaving the line connected to the top outlet of the solenoid, and then blocking off the bottom line connected to the solenoid with a screw or something, how is this different?

Twice i had complete power loss when boost came on at about 3000rpm, it felt like it had stalled hard, like a mini whiplash, but the engine didn't stop, and no lights appeared on the dash. Also it was running excessive boost, bov was louder than ever, and at about 3000 revs boost was up at around .7bar, with only 60% or so throttle, when usually it sits at max 0.5bar under 5k rpm even with the factory 2-stage boost solenoid connected as stock, seemed as though wastegate didn't want to open. Car actually felt very sluggy and hesitant when it came onto boost like it wasn't happy.

Now I have connected it back to stock, leaving the solenoid connected and plugged in. How can i successfully completely remove the stock solenoid and just run the minimum possible boost? Also what to do with the power plug to the solenoid, leave it plugged in or unplug it?

Any helpful knowledge and photos of your setups would be great.

Zombie Collaborator

Zombie

Posted
Posted

I dont really understand the diagram, are attempting to achieve just removing the boost solenoid?

Have you tried just unplugging it? I think it makes it so that you dont get that extra 2psi.

The other method would be connecting the line coming off the wastegate actuator with the spot on the inlet piping and hence circumventing the solenoid.

Adam

Cake Mentor

Cake

Posted
  • Author
Posted
I dont really understand the diagram, are attempting to achieve just removing the boost solenoid?

Have you tried just unplugging it? I think it makes it so that you dont get that extra 2psi.

The other method would be connecting the line coming off the wastegate actuator with the spot on the inlet piping and hence circumventing the solenoid.

Adam

yeah i just want to remove the boost solenoid. i have tried unplugging it but i didn't notice a significant difference which was odd. when installing an ebc, is it completely bypassed, or still has a line going through the top and blocking the bottom one?

thats what i tried, connecting the line off the wastegate actuator to the inlet piping, but there's also that line from the pipe (purple) in pic, bov return i think it is, that's tee'd into the wastegate actuator line -> inlet intercooler pipe. thats when the car ran like shit when it was setup like this.

sewid Grand Master

sewid

Posted
Posted

I left mine in for sentimental reasons and just hooked the solenoid signal up to +12v (ACC) so its permanantly open while the car is on.

Boost restrictions before 5000 are gone.

Been running like this for a long time with no ill effects.

Messiah Mentor

Messiah

Posted
Posted

what mods you running?

keep in mind that the factory ecu has an overboost protection and a fuel cut. i installed an EBC about 2 weeks ago... all went in ok, but when i went to road test i started headbutting the dash every time i cranked up the boost and floored it. so to get the most out of an ebc u need 3rd party ECU or FCD.

My next question is, why are u bothering with this when u plan to install an EBC soon anyway? i'd hold off, check out your options when it comes to yr EBC and just do it in one fell swoop then, the benefits of what your doing now may hardly be noticable.

I use the philosophy of "Dont do anything twice if it can be avoided, and if your going to do anything do it well"

Messiah Mentor

Messiah

Posted
Posted
what is the overboost protection and fuel cut for factory ecu?

dont know the exact figures.... but heres the story.

Installed Eboost and confed it to run 12psi. set up was verified by my bro in law (he builds drag cars so i trust his jkudgement, even if hr has made a car or 2 go pop).

It would accellerate ok until i got above approx 10psi when the OBP (overboost blah blah) and fuel cut kicked in.

this is with stock everything bar EBC 3 inch turbo back zorst and a pod filter.

Cake Mentor

Cake

Posted
  • Author
Posted

Messiah, i have fmic, full exhaust with split dump, pod and that's it.. stock boost control and turbo. when the 2stage stock boost control kicks in it likes to boost right up to .85 or .9 bar sometimes, instead of .6 - .7 like it used to with stock dump and intercooler, i think its boosting too high because the wastegate can't flow enough through my split dump pipe. so i want to disable the stock solenoid to see if it will just stay down at .5 bar even at high rpm, like it does below 4800rpm, sits there perfectly.

here are 2 pics

1st pic is stock setup (how i've put it back to now). pipes in pic are stock intercooler pipes, but i have the hoses going to same places anyway so this pic will do.

2nd pic, is how i attempted to bypass the solenoid. this is when the car ran like shit and was boosting very high, even at low rpm.

what i don't understand is, why does my car run fine when the solenoid has the hoses connected to it, and then when i bypass it, simply by not connecting to the solenoid with the hoses, and running the line directly into the wastegate actuator line it runs totally differently? i must be doing it wrong. basically i just wanna run it like a stock r32 gts-t, which has no boost solenoid stock :P

so the way to do it is, block off the hose coming out of the bov return pipe, and just run the line directly from the intake intercooler pipe, to the wastegate actuator? seems that it doesn't like the hose from the bov return pipe being directly teed into the wastegate actuator line, but is ok if it passes through the solenoid, and then back into the wastegate actuator line. seems strange to me.

one more question, what do you people out there with bleed valves and ebc's do, with regard to bypassing the stock solenoid? also do you leave the wires plugged in or unplug it?

EnricoPalazzo Grand Master

EnricoPalazzo

Posted
Posted

Mate, just do what i said. connect a new hose straight from the wastegate actuator to the intercooler piping. There will be a hose from the BOV return that needs to be blocked. Remove the solenoid as no hoses should be attached to it anymore. also u can pull the plug on it.

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