HELP This Cant be good! ...Boost help please!

[als2]

Right.......
having a chattering DV since i picked her up, changed it today for a forge item.
FINE, chatterings gone, seem to go a bit quicker and idle better, result!.
So next, boost gauge to see whats happening, plumbes into the line going into ECU and off for a drive.
Gauge sits at nearly -1 on idle and just makes positive boost on full throttle!!! this cant be right? surely my ECUs seeing vac on throttle???????
where does the ecu take its boost from?
one thing i noticed when i was changing the DV, this valve seems brand new (see pic) i fitted it as it came off but could this have been incorrectly fitted????
Help would be MUCH appreciated!!!!!!

[als2]

ps. what is that brown valve????

[turbo s4]

n75 valve
tom

[dest]

Is the car boosting ok?
IE, is the gauge telling you less boost than you are actually getting?
Is there defintly no kinks in the pipe to the gauge? (I had that problem!)

The valve in your pic is the WGFV (Wastegate frequency valve), the correct connections are:

Pipe #1 is nearest the WGFV electrical connection and should face the UK drivers side of the car when fitted correctly. Connects to wastegate.
Pipe #2 is directly opposite Pipe#1 and slides into the MAF pipe - this is ALWAYS under vacuum.
Pipe #3 points towards the ground and has the little link tube to the compressor housing on the turbo

This shows you where all the vacuum hoses connect to (assuming you have an ABY)

http://s2central.net/images/Vacuum_and_PCV/ABY_Vacuum_Tree.jpg

[A80Avant]

ECU gets it's boost signal through the green plastic vaccum tube that comes off the inlet manifold and goes into the car. YOu can actually get the gauge connected there with a T piece

[als2]

thanks guys! thats makes more sense and look like the WGFV seems to have been installed correctly!!!
I think i may have assumed that it should have been nearer 0 on idle and positive as soon as u were driving but i gues this might not be the case????
AND............dunno if thisd can be realted but since io swapped over the DV and installed the gauge ive got this weird whine sound, doesnt seem to increase with revs or speed, just whines quite loud, havent been able to pin point it but almost sound like bottom / back of the block or prop shat area. can this be related??????

[dest]

It will only sit at 0 when the engine is off.
Idle should see it in the -, it is not too important by how much as it seems to fary on every engine, and the gauge itself too.
You will only see + on the gauge when it comes on boost, typically between 2-3k on most cars.
On a standard S2 you can floor it at low revs and get "overboost" which gives you a bit more, IIRC its from 3rd gear and above.

[als2]

cheers Dest!!!!!

[Gompa]

is the noise a slight whistle? and does it disapear it you go + on your gauge? if so i bet youve caught the pipe that goes into the brake bomb servo thing in the footwell (sorry dont know its proper name) i caught this when i put my gauge in. hope this is of some use.

[S2central.net]

You should see approx 0.5bar vacuum at idle and when cruising at steady throttle.

Manifold pressure wont go positive until turbo starts blowing - the engine must be under load for that to happen. Expect to see approx 1.1 to 1.2 bar max in overboost on stock S2.

That diverter valve *might* be fitted the wrong way round - post a pic of how it is now.

[als2]

Hi Paul, diverter as in DumpValve? if so its got the pressure side feeding from underneath and side vent plumbed into air intake.
If its the WGFV then its as Dest mentioned its (as pic above) got the electrical side heading to wastegate, opposite to that plumbed into air intake and a hose heading south on the underside piece.
Im thinking this all seem fairly normal now with the boost reading, i gues im actually more concerned that shes now making a weird drone noise, its constant and doesnt raise with engine spped or car speed. does dissapear slightly when u lift of throttle tho. any ideas?????
Just seemed weird that it suddenly appreard after replacing the DV????
(sorry if some of these questions sseem a lil basic but your replies are a great help!!!!!!)
AL

[dest]

So is it making the noise when idling and stationary?

[als2]

yup, it like a fairly low pitch whine, slightly on off (nowt worse than diagnosing a noise over the internet eh??) so id have a guess at something rotating, only thing is there is not increse in speed of the noise as u rev it or drive and most things, pas, ac, etc would all spin quicker when driven.
get marginally louder on pull away then back to a normal noise and lessens slightly on back off.
cant imaging what i might have disturbed or altered??
AL

[dest]

Does it stop/change if you push the clutch pedal down?

[als2]

tried with clutch up and down, doesnt make any differnce, there a couple of places in the rev range that it almost goes away (doesnt change speed, just get quiter)
something loose?
if attached a recording from my phone, dunno if itl come out ok

AL