The AUSubaru.com.au Forums

Hey everyone,

I am trying to plan out how to fix my BOV and boost controller. I tried a "Turbo" forum but they weren't very helpful. Currently the BOV doesn't seem to be working and causing compressor surge (i think). There is no vacuum pipe connected to the BOV, there never has been and I can't find a loose one in the engine bay anywhere. Also, my manual boost controller has had it's screw/bold fall out and lost so I can't control boost pressure and the boost gauge stopped working. I electrical taped it for now which has fixed the gauge. The stock boost solenoid still seems to be connected and I want to either revert it to stock psi settings or disconnect the factory controller and get a new boost controller.

This is a picture of my engine bay. Circled in red is the boost controller. The BOV is connected to the intercooler piping going to the right. I have heard that I need to connect a vacuum pipe from the intake manifold (there are 3) to the BOV but they are all used. How do I go about this? Thanks guys!

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Tee into any vacuum hose for your BOV.

Post a pic of your BOV please.

At the very least, buy a new manual boost controller. Better still, buy a electronic boost controller like GFB.

littlewhiteute wrote: At the very least, buy a new manual boost controller. Better still, buy a electronic boost controller like GFB.

+1 for GFB. You can do just about anything with them

I will probably settle with a manual boost controller as I don't have a lot of money to spend. Is GFB still the recommended on manual boost controllers? Or are there any other cheaper ones? Is the current set up correct with the controller? It seems that the factory boost controller is still connected.

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Here is a picture of the BOV. There is no writing or logos on it so I can't identify it.

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I have a GFB Electronic Boost Controller on my WRX, love it.

Leave the factory solenoid ELECTRICALLY connected so it doesn't log a diagnostic code. You can disconnected all the plumbing when you do a new install of any other form of boost controller.

The top of your BOV has a vacuum nipple on it?

Yeah the top of the BOV has the nipple for a vacuum tube. Where can I buy a splitter and vacuum pipes for my car? eBay has Y-splitters from the U.S but they will take a while for shipping. Would Bunnings have them?

Any good auto parts or plumbing store will have 4mm vacuum tee pieces.

The BOV uses pressure differential to operate, boost pressure on the bottom of the piston (pre throttle body), and vacuum on the top the piston (post throttle body).

Therefore on boost, no vacuum, so valve is closed.

At light throttle, no boost, high vacuum, valve is closed.

Engine has had boost, then throttle is closed, valve open.

Prevents compressor surge.

OK, I will check out some auto stores tomorrow. For installation, I take any of the vacuum pipes, cut it, connect the tee, then attach another vacuum pipe to the tee and the BOV?

Disconnect one while the motor is running.

If there is vacuum present then you can tee into that hose, then to the BOV.

Success! sort of... The BOV is working now but only at high rpm and boost. Could this be because the BOV is too "tough"? The car still makes the "compressor surge sound" even when the BOV kicks in or not.

Tomi wrote:Success! sort of... The BOV is working now but only at high rpm and boost. Could this be because the BOV is too "tough"? The car still makes the "compressor surge sound" even when the BOV kicks in or not.

More than likely the spring is too heavy.

If it is a no-name valve, chuck it and fit a turbosmart or something decent that you can disassemble for cleaning and adjustment etc.

Tomi wrote: Here is a picture of the BOV. There is no writing or logos on it so I can't identify it.

I don't suppose you have noticed all the crap in the BOV, look at the hole in the middle of the picture there is a good chance it is jammed and thats why it is only working at high rpm and boost.

TOONGA

At the start, I took the BOV off, cleaned and sprayed oil in and around it. I am able to move the cylinder with enough hand force. Could I get a weaker spring to put in the BOV? If I end up getting a new BOV , which brand would you guys recommend?

If you can push the piston with just the force of your hand them it will work fine. Too weak and you'll loose boost through it.

I'd recommend TurboSmart or Go Fast Bits (GFB)

You can actually run the factory boost controller and trick it into being an adjustable electronic controller. it costs about $1.50 in parts and about 40min of your time.

- STOLEN FROM ANOTHER FORUM -

"I thought I would post up some info on how I have upped the boost to 12 psi using the stock system in my SF. I came across this site http://www.autospeed.com.au/cms/A_110897/article.html while looking for a way around the fuel cut at 10 psi (while using a aftermarket boost T). It got me on to thinking I could use this to adjust the Map sensor just a little so I could run 12 psi with the manual controller and no fuel cut but still have the cut just at a higher level.

So I went to Jaycar and got a 10 kilo-ohm trimpot soldered 3 wires on to the 3 terminals and ran a test using a aa battery and a multi-meter to figure out which wire was what and make sure the trimpot was fully open (full voltage passing through).

In my case I had GREY to Ground, White to Source and White/Black to ECU. Using a ECU pinout I cut the MAP sensor signal wire and wired in my white and white/black. The Grey to earth.

I did some on road tuning and found it was working well. Then I thought I wonder if I could use this without the Manual boost controller. I ripped out my Boost T and in no time had the foz running 12 PSI using the stock system. This is great as now I wont need to tell my insurance company that I have a boost controller saving me $$.

Anyway I though I would put this up for anyone else looking for a way to play with their boost on the cheap. I would say this was a pretty easy mod for most people.

I also put enough wire on my trip pot that i could mount it in a accessible safe spot under the dash for ease of adjustment."

This is what i do with mine and is really your best and cheapest option.

Cheers,
S