Raghza's '96 Legacy GT-B

[Raghza]

Alright so after about 120km of city driving my normal boost changed back to 0.5 bar again. And again, I had the code 65 (DPS). So today I tried to clean the DPS, but ofcourse, this had no effect so now I'm getting a constant CEL with code 65. I'm gonna change the DPS and hope it will fix that like it's supposed to.
But I also cleaned the solenoids and during that I discovered that I have one unconnected hose connector in the box. It's the one marked with red on this picture:


Everything else is connected like they should, but only this solenoid has one free connector. Could this be the reason for my boost problems too? If so, what should connect there and where?
I don't have that black plastic thing there (the one with red dot), but just an empty connector. No loose hoses anywhere though, that I could connect there.

[slaytalera]

Nice car! Im very interested in how the LHD swap was done, it might allow us in LHD parts of the world do GTB swaps and no go through the hassle of going RHD

[Dead91silvia]

If I get some time, I might see if I can pull my box out and look, but this is the only car I have insured for driving (other then my big ass truck). So it's a little hard.

But yeah, they are finicky systems so one line would mess something up.

[Raghza]

Thank you, that would be awesome.
But about that DPS again - turns out it's not that easy to find one, if your car is pretty much the only one in the country. So if somebody from UK has one in spare, I would pay good money for it. Or if somebody has two, I would take two, just in case.
And ofcourse, any other information like the part code for the sensor would be great too, so I might try my luck finding it from some parts dealers in Estonia.

[Raghza]

Been a while since my last post.
Anyway I changed the DPS and got rid of that error and after another ECU reset the boost levels were back to normal.
But ofcourse, soon after that it went back to 0.5 bar again. However when I'm in 2nd or 3rd gear and give it full throttle, then backing off, then full throttle again etc, I get 0,6 bars for a few moments. I also checked for fault codes and had none, so I guessed it can't be due to the limp mode.
Today I unplugged hose 23 at the T-piece and went for a short drive. The boost went up all the way until I backed off at 0,7 bars, because I was afraid of overboosting. So no more 0.5 bar boost limit with hose 23 disconnected, so it must be my boost control solenoid in the wing that's stuck in the closed position?
I disconnected hoses 10 and 23 and sprayed a lot of carb cleaner into them and then blew it out with an air compressor.
However, I absolutely could not find the second green connector to make the car go into test cycle, so I was hoping that just cleaning the solenoid would do the trick. It didn't.
So what's my options? Can I just spray some cleaner into the solenoid, connect everything back together and go for a drive? Would that cycle the solenoid too as well as the test cycle?
I don't want to have another ECU reset, because it results an awful fuel consumption.

[Raghza]

Although I'm still struggling with boost levels, things are starting to make sense.
I even tried a manual boost controller, hoping that it would sort out my problems, but this thing was impossible to set up properly. I got very high unstable boost on primary and still only 0.5 bar on secondary.
So today I connected everything back the way it came from the factory and managed to clean the boost solenoid with carb cleaner and cycling it by connecting 12v straight from the battery to it. Luckily, it was working fine, so I'm really happy about that.
During a short test run I still only got 0.5-0.6 bar on primary and 0.5 on secondary so tomorrow I'm gonna refurbish the solenoid box and check the pressure relief valve to make sure it's working. So if I still get no results after cleaning the BBoD, it must mean that the relief valve is dead, which leaves me with only one thing that needs to be changed - happy times!

Just one random pic from a local Subaru meeting


You may notice that most of the scratches on the rear bumper are gone - I did some touch-up painting and the results were actually really good. Some deeper scratches are still visible, but it's a lot better than before.

[Reuben]

Oh good god, that is an image of my nightmares....

[Dead91silvia]

Oh good god, that is an image of my nightmares....

I'm gonna get one, take it all apart and send you the pics!

[Raghza]

Haha
That's just a random pic from Google, not my BBoD, although mine does look a lot like this (I also have the Nutbeam NSS box with blue silicone hoses).

Anyway, is there anything else I could check besides the supercharged pressure relief valve?
I'm not gonna rewrite my boost problems, because you can read it HERE.

[Reuben]

Oh good god, that is an image of my nightmares....

I'm gonna get one, take it all apart and send you the pics!

Been there done that, it's the fact there's no numbering on the tubes.....

[Sub-Goon]

I dont know if its already been mentioned, but here goes! Each one of those paint stripes marks a vacuum restrictor! Each color represents a certain size oriface. Some components require less vacuum than others. You can cut them out of an old hose, lube them and squeeze them into the new hose, just use a dental pick or piece of wire to make sure it stays aligned and doesnt rotate, clogging the line. Hope this helps!

[Raghza]

I have a totally different question - I need a new supercharged pressure relief valve, but it's impossible to find in Estonia. Is there some other Subaru, that has the same part that can be fitted to my GT-B?

[Muse]

Would that be the same as a wastegate or blowoff valve?

[Mark in NZ]

It's a BOV

Early WRX BOV's look identical - so do the early legacy TT ones actually

Short term fix is to simply block the valve inlet or outlet with a decent sized bolt or something - it does affect the VOD a bit but is much less harmful than having it jammed open

[Mark in NZ]

To be honest you could probably get away with almost any kind of recirculating BOV if it fits - that valve functions exactly like a BOV, only difference is it is deliberately kept open under 4500 to let the secondary free spool - above that it is closed. If you block the valve off, it means the secondary can surge a little bit and won't be as up to speed when the intercooler valve opens up - I had to do this for a week or so myself when I snapped the vacuum fitting off the SC relief valve - I have a BH and I'm pretty sure the replacement was from a BG

[Raghza]

Whoa, that's a nice answer, thank you!
I'll try to block it first to see if it fixes my problems. And if it does, which valve can I replace it with? I'm sure I won't be able to find one from a BG or BH as all we have in Estonia are naturally aspirated versions of these cars.
The reason why I am skeptical about replacing it with e.g. a WRX BOV is the reason you mentioned - it's kept open under 4500rpm and closed after that. So by replacing it with a different one from a different model, wouldn't it operate differentely, therefore messing up the whole sequential turbo system?

[86bratman]

Awesome car, I'd be interested in seeing some up close pictures of the area around the secondary turbo. That is the big trouble spot for a lhd tt swap, your car has the answers already lol. If you have time to get some pics that would be great

[Raghza]

Sure, I'm gonna go and mess with the relief valve anyway some time today, so why not, I'll take some pictures.

[Reuben]

The reason why I am skeptical about replacing it with e.g. a WRX BOV is the reason you mentioned - it's kept open under 4500rpm and closed after that. So by replacing it with a different one from a different model, wouldn't it operate differentely, therefore messing up the whole sequential turbo system?

No. There are indeed many types of the subaru 19mm bypass valve, good ol red sticker ones from the EJ20G's, and the different variations found in twin turbos. While mark is right on the fact they are essentially just a standard bypass/blow off valve, a few things are different between them. the only visible difference is the orientation of the vac line, but that's a null issue. What we don't know is, are the springs inside different tensions, and can this affect it's operation?

To answer your question though, probably no. It is just a bypass valve, the operation is controlled by the solenoid box, so that should still work. The only thing that would stop it working is if spring pressures inside the valve were different enough to prevent it opening and closing on command from the solenoid box.

They are easy as for us in NZ to get, I can quote you a BG one specifically for that purpose, and you can paypal me, I'll have it sent direct to you from my preferred wreckers. They may even be able to accept paypal directly.

HOWEVER, I'm not convinced that will fix your problem, my eyes would in fact be trained on all that blue unidentified vac line. Quadruple check that it's actually all hooked up correctly! And yeah, the vac line pills, def need those in there. You have tampered with the spaghetti monster, this can only ANGER it, and it will exact revenge on you by throwing error codes and confusing the fuck out of you! enjoy!

[Raghza]

Thanks again for the reply, I feel like I'm really getting smart here
By the way that picture above is not my BBoD, it's just off the internet. I haven't relocated any hoses in mine, so everything is just the way it was when my boost was okay.

Anyway, I made some pictures. Sorry about them being so ugly, but my garage is a bit dark so I had to use flash, which made everything really dirty (I like to keep my engine bay clean).
So this is the picture of the relief valve we've been talking about. It has a small hose going to it (marked blue), then a big hose on top (marked red) and another big hose at the bottom. I just pulled off that big top hose, blocked it and put it back together. Did I do right or should I have blocked something else? Before blocking I could easily blow through it.
There's also this mysterious screw (marked ? ) that has always been there. I wonder what's it for?


And now those other pics.
That's my engine bay:


The area of the secondary turbo:



The area of the primary turbo:



And just a picture of her sitting in a garage:

[86bratman]

Wow thats a tight fit, at least it shows that its possible. Thank you.

[Raghza]

Alright I'm back from my test run with the relief valve blocked and no positive results once again.
I get ~0.7 bar boost on primary and sometimes it stays there until the VOD, sometimes it slowly drops back to 0.5-0.55 bar. But no matter what, when secondary kicks in, it goes okay and without any strange noises (I'm positive that both of the turbos are in good condition and working well), but not nearly as fast as it should be. On secondary, my boost gauge shows 0.5-0.55 bar.
What else could I possibly check? My vacuum tank for leaks perhaps?

[Reuben]

No positive results because it shouldn't be blocked! I would have thought that fairly obvious...

That screw is in place where a vac nipple should be, you need to replace that top pipe with one that has both its vac nipples, and plump it in correctly. Then you should be home and hosed.

I can track down that pipe for yah and send it over if you want. Should be free of charge.

[Raghza]

Oh, I wouldn't have thought that another vacuum hose is supposed to plumb in there. It used to work just fine being the way it was, but yeah, I definitely need to replace that.
Are you sure you want to send it to me from NZ? I would appreciate it very much, but I have no PayPal account - perhaps you could PM me your details and I could just transfer some money to you, to cover the postal charges?

Btw, if there's another vacuum hose, where should the other end of it go? I don't think I've seen any loose hose connectors anywhere, so perhaps it's meant to T into some existing hose?

[Telemekas]

The nipple has broken off where Hose No:22 should go.This has been blocked off with a screw.
Hose No:22 is now plumbed into Hose No:16 with a T connector.That is OK and should not be causing a problem.
Hose No:16 and 22 are measuring boost only.



Solenoid box (This is for the early GT model)

[Raghza]

Thank you I thought that it wouldn't matter a lot.
But can anybody help me with my problem?
Could it still be the supercharged pressure relief valve? When I blew air in it, it easily went through, but blocking the valve as suggested did not change anything. Should I replace the valve or look for the answer of my problems elsewhere?

[Reuben]

As long as those vac lines do what they are supposed to, then yeah, maybe back to square 1, and replace the bypass valve.

[Raghza]

Hmm well, I just checked the fault codes for no reason and it showed code 65. I had it before and then I replaced the DPS.
Could it be that somehow my previous ECU resets haven't cleared it and that's the reason I'm getting no boost, as the car is still in limp mode?
Or could something else than the DPS also cause error code 65?
I'm gonna try to disconnect the battery for overnight to make sure the ECU gets properly reset. If the code is still there, then I have no idea...

[Reuben]

Hokay...
Did you ever get an error code for the secondary bypass valve, or was it only ever 65-dps. And what exactly are the symptoms when driving, is it just that it boosts 0.5 and 0.5? A BG should boost 0.7-0.8 (10-12psi) primary, and 0.9-1.1 (14-16) secondary. When we know what it is currently doing, know the ECU code it's throwing, and know what it's supposed to do, we can start applying logic to the TT system.


What does the DPS do? It measures how much boost the secondary is making while the intercooler valve is shut, and compared it to how much boost is going into the engine from the primary. It also tells the ECU that the intercooler valve has sucessfully opened when on secondary, as it will measure equal boost from either of it's vac lines.

So, what else could cause a DPS fault code, when the DPS is fine. Possibly the intercooler valve isn't opening? this could cause a fault, as when it is expecting equal pressure, it's not receiving equal pressure, so the code will be tripped as the sensor showing numbers outside the expected range. The fault in that example could be a sticky intercooler valve. I've also seen many many many valves gummed up terribly with oil from blowby in the intake, as well as oil creeping through vac lines in old systems.

What else... The secondary bypass valve could be leaking, meaning that the boost the secondary should be showing the ECU could be down (pressure is a result of flow being impeded, if flow impedance drops, pressure drops). This is also a terribly common issue, as the seals in these valves get old and perish pretty quickly, even 5 years ago when I got my twin turbo, this was already common as mud. Us kiwi's have a nickname for this problem, it's called "george". It's been dubbed with a human name, because the problem shows itself as a humming noise, long before it will ever trip any codes. The hum happens when on primary, while under load, the secondary will be starting crossover phase, and the valve will be closing, the humming is made as the valve tries to seal, but air is still getting let through. Bit like when you put a blade of grass between your thumbs as a kid, and blow through it to make that annoying humming/trumpet sound.

You could also have solenoid or other valve issues. If the valve is trying to open, but can not, be it stuck, or the solenoid that opens it not working properly, then the pressures the DPS are expecting to see could be out of wack, again. This could be caused by blocked vac lines, blocked solenoids, dead solenoids, blocked valve, dead valve.


Try and see when the problem exhibits itself, and figure out what phase the motor is in, this should indicate what part could be causing issues. If the check engine light pops on at any time intermittently, again, figure out what the phase is, and it should tell you when and where the problem is.






This ladies and gentlemen is why twin turbo sucks, and why I single every TT that I can.

[Raghza]

Oh wow, again, thanks a lot for your reply.

The only error code I've ever gotten is code 65. I then cleaned the DPS with carb cleaner (a huge mistake, I know) and got a permanent CEL, so I replaced the DPS sensor and then checked for error codes and got nothing. So I thought it's gone.

The only symptom I knew I had, was 0.5 bar boost on primary and secondary. I have some Nutty mods and 3'' exhaust, so it used to boost 0.7 on primary and 1.2 on secondary.
But now that you mention it, I do get this terrible humming noise while under load on primary. The hum was a lot louder, when the car was working fine, but now with 0.5 bar I rarely hear it (only sometimes when driving up a hill and I manage to get ~0.55-0.6 bar on primary. By the way, describing this sound like you did with a blade of grass is absolutely the most accurate description to it I could think of

I haven't replaced my supercharged pressure relief valve and I believe that it's broken, since I can blow air through it, but I never knew that it could also throw code 65.
So I guess what I should do, is reset the codes, watch for error 65 come back again, then replace the secondary bypass valve (it IS the supercharged pressure relief valve, right?) and hope things get better after that?