Removing Dump Valve

[driftin jo]

The metal pipe in the 3rd pic is of part the breather system and is standard, however if the other end of the dump valve is not connected to the boost pipe somewhere then you will be getting compressor stall, whether or not you can hear it is another matter as you may be hearing hissing as it is quite likely on an S2 to boost leak when you shut the throttle if you don't have a dump valve.

[Error404]

Thats the breather pipe from the cam cover

[205gti]

The metal pipe in the 3rd pic is of part the breather system and is standard, however if the other end of the dump valve is not connected to the boost pipe somewhere then you will be getting compressor stall, whether or not you can hear it is another matter as you may be hearing hissing as it is quite likely on an S2 to boost leak when you shut the throttle if you don't have a dump valve.

If by the other end of the dump valve you mean the vacum line then thats connected fine. I dont believe there is a boost leak as its boosting to 1.4/1.5 bar fine. It sounds like the atmospheric dump is working as it should as its louder when there is more boost and has the distinctive dump valve sound. Correct me if im wrong but doesn't compressor stall sound more like a fluttering which people sometimes refer to as a "pigeon" noise?

[driftin jo]

how can it dump boost from the turbo inlet , no offence but it's impossible, what I have said above is the only plausible answer to you hearing boost when you shut the throttle, I'm not talking about a boost leak when you have your foot down just that when you back off, the turbo is trying to get rid of ~150 litres of air per second and you will have very high pressure if you don't have a working dump valve hence it will leak where it can.

[Error404]

are sure some muppet hasn't tried to plumb 2 dump valves in and you've only found one of them?

[Jamo]

For the dv it should be in that samco hose and the connection is the dv outlet, the inlet should connect in-between the turbo compressor outlet and the intercooler inlet there will be a long pipe of it
Forget all this noise crap aftermarket valves can be noisy what you need to check it has setup as a recirculate and some Chav hasn't tried to install a to atmosphere valve

[205gti]

No i totally understand what your saying. I can see myself that the dump valve is before the air even reaches the turbo so it wont be pressurized. Now i'm going to have to re-install the stuff in the correct place. The joys of buying a readily modified car

[205gti]

how can it dump boost from the turbo inlet , no offence but it's impossible, what I have said above is the only plausible answer to you hearing boost when you shut the throttle, I'm not talking about a boost leak when you have your foot down just that when you back off, the turbo is trying to get rid of ~150 litres of air per second and you will have very high pressure if you don't have a working dump valve hence it will leak where it can.

No i totally understand what your saying. I can see myself that the dump valve is before the air even reaches the turbo so it wont be pressurized. Now i'm going to have to re-install the stuff in the correct place. The joys of buying a readily modified car

are sure some muppet hasn't tried to plumb 2 dump valves in and you've only found one of them?

I will have to take a look. I couldn't see anything else but if someone was stupid enough to put one before the air reaches the turbo they are probably stupid enough to install 2.

[driftin jo]

are sure some muppet hasn't tried to plumb 2 dump valves in and you've only found one of them?

now that is possible

[Rusty]

Ditch that cone filter too; it'll just be sucking in hot air unless it's very well shielded.

Best thing to do is to put it back to standard and then decide what you want to do. A spare 710N in the glovebox as a spare is a good plan anyway

There should be a pipe that comes up from the turbo to IC hose - this is the connection on the boost side.

[205gti]

I think I have found the pipe that comes up to the bottom of it. Im guessing its the one you mean from the intercooler. There doesn't seem to be anything on it to switch from atmospheric to recirculate though.

[Jamo]

If it's connected to the dv then it's setup correctly

[205gti]

Yea it seems to be. Thats that solved then. Now all I need to do is replace it with a proper recirculating one.

[driftin jo]

[newsh]

Thats where the DV should be returning to, are you sure there's not another pipe coming off the bottom of it? You're going to hear loads of intake and DV noise because you have a cone filter, changing back to a stock ABY airbox will sound a lot quieter and will work better too as it draws cool air from behind the headlight rather than warm air floating up from the turbo and EM.

The piece of metal you're seeing is actually a pipe, it connects the breather system to the MAF hose, all good there

Edit: Ooops just seen all the replies

That's what happens if you go and read codes before relying to a post ..

Anyway, I reckon your car is fine and running a diverter valve, you're just hearing it working through the cone filter.