Help sorting my underboosting S2?

[prj]

yes, there was loss but no smoke coming out anywhere so we assumes no leaks (externally anyway).

Use soap water and spray everything down.
Block the breather system.
Block the line going to the wastegate.

Try again.
You have a plain old boost leak. It needs to hold 0.5 bar for at least 20 seconds when you pressurize it from the MAF and block the breather system & wastegate.

[gunman]

Thanks guys. I will give it a go but it'll be at least a week before I get enough time to do this, away this weekend and working all next week.

I think I may need another boost leak test kit as I cant find my other one.

[Rusty]

Have you checked the injector seats? I've just had to tighten one up.

[prj]

Have you checked the injector seats? I've just had to tighten one up.

If the injector seats are loose, then "tightening them up" won't really solve anything.
Plastic and metal don't seal very well. The way to go with the injector seats, if one of them is leaking, is to remove all of them and fit brand new ones.
When fitting brand new ones, wrap their thread with teflon tape and firmly screw them in.

Also, when removing the old ones one should put a rag or something like that into the manifold to prevent the plastic bits from falling in (they /will/ break).

[Rusty]

Funny how tightening up the loose injector seat solved the issue then Must have been witchcraft.

Using teflon tape is a good plan to seal it and stop them coming loose.

[prj]

Funny how tightening up the loose injector seat solved the issue then Must have been witchcraft.

They are supposed to be glued in. If they already came loose, it means that the sealant has let go.
If you pressure test the intake to higher pressures and spray liquid soap on them, I am sure you will see bubbling. I don't care how hard you tighten them.

BTDT about 20 times now.

[stocious]

can outa phase cam/crank cause low boost symptoms ? as he mentioned he had idle problems also ! is the closed throttle switch tied into to boost ?

[prj]

can outa phase cam/crank cause low boost symptoms ? as he mentioned he had idle problems also ! is the closed throttle switch tied into to boost ?

It can cause limp mode only. Meaning mechanical boost.
The issue in this case is clearly a boost leak, as soon as they disconnect the pressure line the boost drops.

It should hold 0.5 bar for about 30 seconds EASY. And there should be still residual pressure in the system after 1 minute.

So I think there is no point to guess here...

[stocious]

understood and thank you, it was more wanting to know.. learning everyday..

[prj]

Well, because you are posting in his thread it is naturally assumed that your remark is aimed at his particular car
But yeah, these ECU's are pretty simple. If they do not like something electrically you will have spring boost. Like the N75 is disconnected, which is effectively what it is, as it just disconnects the N75 in software.

If you have boost higher than spring pressure it means that the ECU is not in limp mode and is controlling the pressure. The fact that it can not attain said pressure usually stems from mechanical causes.

[gunman]

Thanks for all input guys, I'm afraid I haven't had a chance to do much yet, I hope to be able to take the car off the road for some work in the next few months. I intend to rebush the rear end at the same time.

I still need a boost leak test kit and will prob test in sections if the fault isn't obvious.

Cheers

[Rusty]

Have you disconnected your N75 valve to check the spring boost is ~0.4 Bar?

[gunman]

yep, did that and got 0.4bar.

[Rusty]

1 way valve at the rear of the engine that connects the N80 T piece to the breather? If that's knackered
then it'll short circuit the high and low boost sections as per a knackered DV. Will also leak during a leak test if the breather is blocked but contain the smoke in the system. Just a thought...