Turbo setup help, is this ok?

[pringle1988]

Hello all,

Its been a few weeks since ive asked for help from you lot so its about time I asked for more help. This will probably be a very novice question to some of you but here it goes.

Basically when I purchased my current car the breather hoses on the turbo and intake were not standard. Ive drawn up a highly detailed diagram of what it is currently like below. The engine is a SR20DET if that helps.



The solenoid has been bypassed and in its place is what looks to be an airline fitting. Is this some attempted at a bleed valve? What is going on here? Im pretty sure its boosting way over stock according to the boost gauge.


Below is how I think it should be set up. If somebody can confirm this id be greatful as im going to put it back to stock for now. The red is a plug and the blue is air line





The reason im putting it back to stock is I seem to have a limp mode on the car where I can only rev to 4000 RPM. The consult port comes up with the code Mass Air Flow but could the setup be causing this?

Thanks in advance all im just starting to get into the world of turbos.

[TheEnd]

Is it a positive pressure wastegate?

Looks to be one from the drawing, and in that case I'd say it was probably a boost bleed valve which was the odd new bit.
Instead of the ECU and solenoid controlling the wastegate, it takes the raw pressure from the manifold, and bleeds off the boost to hold the wastegate closed for longer.

The original way looks like it bleeds off pressure into the intake and shuts the solenoid to push open the actuator when the ECU has had enough.

[pringle1988]

Thanks for that. I knew nothing other than the very basics of how a turbo worked untill recently so slowly learning. That does make sense what you said though. Ive heard that it is a very common mod on this engine aswell. The bleed valve on mine looks very home made though which is why it raised a concern.

[pringle1988]

Can anybody confirm if how I think the stock setup is is actually correct?

[227bhp]

Pictures - good ones.

[pringle1988]

Hopefully these are good enough. If you need to know where some of those hoses are coming from or going to I can try to answer.







That bolt you can see is the plug for the pre turbo intake. The other side from the solenoid is just left open as it has nothing connected to it other than the wiring.

[227bhp]

pringle1988 said:

Hopefully these are good enough. If you need to know where some of those hoses are coming from or going to I can try to answer.







That bolt you can see is the plug for the pre turbo intake. The other side from the solenoid is just left open as it has nothing connected to it other than the wiring.

On the original boost controller is a pipe coming out of the end, where does it go? It's difficult to see if it's just laying there or goes into the larger pipe, but i'm guessing it is the former. So there are just two pipe outlets on the solenoid?

The valve in your pic is a ball and spring type boost controller, it isn't really a bleed valve (these have three legs) as it isn't wasting boost, you can find them on Ebay for a few quid. Basically the boost feed from the turbo has to overcome a small ball bearing which is being held down by a spring (like one from a pen), once it's lifted the ball it goes through the outlet and operates the wastegate (WG) via the actuator. Tightening the screw (clockwise) will make it harder to overcome the spring pressure and so the turbo will be allowed to produce more boost before the WG opens and stops it.

So there is one way to reduce the amount of boosted air the engine is getting - turn the adjusting screw anti-clockwise.
The other is to take the pipes from it and put them back onto the original, here you will have a slight issue if you don't know which way round they go.

Edited by 227bhp on Tuesday 4th August 22:13

[pringle1988]

Yeah just 2 places to put a pipe on the solenoid. The pipe you can see connected to it doesnt go anyway so you were right with the former, but in stock form should go into the intake just after the MAF and before the turbo. I think there is a 'T' piece which comes off the top of the solenoid into the intake after the turbo with the wastegate acuator going into the bottom of the 'T'

[227bhp]

pringle1988 said:

Yeah just 2 places to put a pipe on the solenoid. The pipe you can see connected to it doesnt go anyway so you were right with the former, but in stock form should go into the intake just after the MAF and before the turbo. I think there is a 'T' piece which comes off the top of the solenoid into the intake after the turbo with the wastegate acuator going into the bottom of the 'T'

I edited my post with a bit more info. You just need to know what standard boost pressure is, it's probably about 1 bar, then start from there.
I don't think the pipes will go as you've outlined if there are only two - the two on the MBC will go onto the OE solenoid.

[pringle1988]

Ahh thanks for the explanation into what that fitting is. It makes perfect sense. I might try turning it anti clockwise untill the boost is at about 1 bar. At the minute it goes off the gauge at some speed so ive no idea what its doing.

Can this cause the engine to basically put itself into a sort of limp mode and cut revs to 4k? Just thinking if there is some sort of fuel cut if the boost is too high and it hasnt been mapped to chuck in more fuel? I could be way off the mark there however. Only 1 way to try I suppose.

[pringle1988]

Thanks again for the replies, just thought id update to say the reason it was cutting out at 4k rpm was a fuel cut as the boost controller has seized and the little vacuum hose burst. Its back to stock now and only boosting 7psi but at least I can rev again.

Anyway im now after an electronic boost controller now something like the Greddy Profec or similar.