Low Boost (0.35 Bar) Rb25Det

[Tungstenaxe]

Hello, I've some wierd issue with my car. I only get half boost pressure(?). I've looked over the vacuum hoses, looked after leaks around the pipes.. But it all looked good. Also checked the ECU and had no fault codes. I have no mods other then a SSQV and some aftermarket air filter.

I hope this is the right Forum part to ask this.

Thanks.

Robbin

[Ben C34]

What gauge are you using?

Looking for leaks is pretty pointless as you won't find them. You have to pressure test to find them.

Search pressure test for boost leaks on Google to see how to do it.

And put stock bov back on....

[jiffo]

Hard to diagnose faults like this on the net but you're getting 5psi which is waste gate actuator pressure for a stock setup.

Is the "high boost" bleed solenoid plugged in and working?

[Dose Pipe Sutututu]

0.35bar / 5 psi is pretty much gate pressure (without the factory bleed 2-step boost controller).

As jiffo mentioned, could be either blocked lines to the bleed OR the solenoid is not plugged in/faulty.

[GTSBoy]

Alternatively, 0.35 on the dash gauge is of course 350/760 mmHg, which is 0.46 bar and is almost spot on the correct 7 psi boost pressure.

[Ben C34]

Exactly

Which is why I asked which gauge op is using.

[Tungstenaxe]

Sorry for late answer! I was at work.

Thanks alot for all the answers. I have been trying to google the answer but still haven't found anything yet, and you all seem experienced so.. .

I'm using an aftermarket gauge, i have tried two different ones and both showed the same. Also tested to plug in some old Apexi EBC and got the same boost with that one aswell, that one also showed how much boost i had, and i topped almost 0.4 bar. I have tried a mechanic boost controller aswell but i'm still stuck with the same boost pressure.

I'm using the high boost mod btw, by grounding the black cable that goes to the solenoid.

I'm gonna check over the hoses again and see if i connected them right. Found another picture on the internet now so i'm gonna try that first, so i'm sure i just haven't connected em all wrong.. let's just hope that it is that easy thou .

Thanks alot for the help so far, i'll be back later today to keep you updated!

[Dose Pipe Sutututu]

if you have an EBC.. just delete that factory boost controller setup... it's not ideal as it is set up to bleed pressure from the actuator pressure line

[GTSBoy]

if you have an EBC.. just delete that factory boost controller setup... it's not ideal as it is set up to bleed pressure from the actuator pressure line

Um...that's what EBCs do too you know. It's just that you can change how much. The 3 port solenoid alternately connects the actuator to boost source and to vented port as the valve opens and closes on duty cycle. If you plug the vent port, EBC does very little. They are still just a glorified bleed valve (when connected to a factory style actuator anyway).

Having said that, I agree with your sentiment. Install old EBC and be happy. Although it sounds like the OP problem may in fact be a plumbing problem anyway. We shall wait and see.

OP, draw us a sketch of where the hoses come from and go to.

Edited June 12, 2014 by GTSBoy

[Dose Pipe Sutututu]

hrms...

I always thought the way those solenoids worked was to restrict a pressurised source going to the waste gate thus stopping it from opening, once the desired pressure is reached, the EBC controller then sends a signal down to the solenoid to pulse so just the right amount of pressure to open the wastegate.

I didn't think EBC bled air, it depends how you connected the ports, happy to stand corrected

(I use a Blitz dual solenoid)

[GTSBoy]

I have a Profec B which just uses the normal old MAC valve. That valve is 3 port. If it is un-powered then the NO port is connected to the COM port. NO is from the boost source, COM goes to actuator. The NC port is left open. They pretty much have to be plumbed up that way so that when the boost controller is switched off then the boost source is always connected to the actuator. Otherwise you'd have no boost control.

If you power the solenoid it connects the NC port to the COM port - ie, it vents the actuator line. The pulsing by duty cycle simply determines how much it vents. if the duty cycle is low then it spends more time connecting the boost source to the actuator. If the duty cycle is high, it spends more time venting the actuator, hence lowering the pressure in that line.

It's actually pretty crude from a control theory point of view. But it seems to work.

I've looked at the Blitz dual solenoids before and wondered where they vent the air to, given they only have 2 obvious ports.

[Dose Pipe Sutututu]

^ great explanation as always

I was under the impression that worked like how I described, restrict pressure going to the actuator - appears I might have been incorrect. However, these EBCs still work better than your run of the mill turbogaids dual stage bleeder controllers.

I might take apart my dual solenoid and see if there are internal "vents" as such, the casing isn't air tight/water tight so it could just vent into the housing and escape somehow (if it similar to a MAC valve).

[GTSBoy]

I just did some googling and someone else on another forum was saying exactly that - that the Blitz dual solenoids (in particular) vent internally.

http://www.imoc.co.uk/forums/viewtopic.php?t=177171&postdays=0&postorder=asc&start=20&sid=2026d2255059bb38935b584254f96051

And that also explains why the Blitz dual has a mode switch on the controller itself to choose between actuator type and external type control. On actuator mode it works the solenoid as I describe and on wastegate mode it inverts the operation of the solenoid so that increasing duty cycle increases the amount of boost allowed through to the wastegate (because externals are commonly run and plumbed differently to internals).

[Blackkers]

I've got a spare RB20 actuator which will bolt right on and give you 9-10 psi.

Not sure how much theyre worth but it's not doing much in my ever growing pile of spares

[scotty nm35]

Exactly why I run 5 port MAC valves. Both hoses vent separately.

[Tungstenaxe]

Thanks for all the answers, you sure know what you are talking about . Glad to see that so many take their time and help.

I connected a hose from the intercooler pipe to a T, then to the bottom slot on the solenoid, and The other hose from the T to the wastegate. Then i connected a hose from the top slot on the solenoid to the pipe under the intercooler pipe (recycling pipe?)

Still Low boost, I'm at work till late tonight, so I guess I'll try to plug in the ebc if i get some time over (I'm running stock solenoid now).

Will make a better post when i get home and have time .

Thanks again all!

[KiwiRS4T]

Thanks for all the answers, you sure know what you are talking about . Glad to see that so many take their time and help.

I connected a hose from the intercooler pipe to a T, then to the bottom slot on the solenoid, and The other hose from the T to the wastegate. Then i connected a hose from the top slot on the solenoid to the pipe under the intercooler pipe (recycling pipe?)

Still Low boost, I'm at work till late tonight, so I guess I'll try to plug in the ebc if i get some time over (I'm running stock solenoid now).

Will make a better post when i get home and have time .

Thanks again all!

You have plumbed it correctly but in the stock set up there was a restrictor in the line from the intercooler pipe so without the restrictor there will be more air keeping the wastegate open (and so less boost).

If you can get the EBC working that should do the job.

If not grab the RB20 actuator on offer (shouldn't be too expensive) and again bypass the stock solenoid.

Or a cheap boost T would be better than nothing.

[Tungstenaxe]

Oh, so there can be some problem with the restrictor?. Or did i get it all wrong? Haha

[KiwiRS4T]

Oh, so there can be some problem with the restrictor?. Or did i get it all wrong? Haha

Not if you put all the stock lines back in. I was assuming that you didn't have the stock lines and just used some new hose which didn't have the restrictor.

[Tungstenaxe]

Yeah i use new hoses. However, i tried to put a hose on the wastegate and blocked it just to see how much boost i could get.. and i still get around 0.3 - 0.4 bar.
Is that the right way to get max boost? or what should/could i try more?. I'm starting to wonder if it's the catalytic converter that blocks too much? it's taken from my brothers Volvo V70. But maybe that doesn't affect the boost at all?.

I recorded a video on my way home from work too show you how the car/boost acts. Was driving while holding camera but i'll guess the video works

Thanks again all . Edited June 13, 2014 by Tungstenaxe