Wastegate Settings

[martinjs]

Im trying to get the root of my running problem (still ), loss of boost/power at 5k, not a violent cutout though a la major boost leak.
anyway im now looking at my wastegate, the spring was cranked right down, so first i disconnected the WGFV and got 0.4bar and would rev to redline.
i thought this was a bit low??
so unwound the screw back to stock settings and am still getting 0.4bar with WGFV disconnected!! so basically adjusting the spring to whatever setting makes no difference at all...any ideas?
shot WG diaphram?


martin

[newsh]

If your diaphragm was shot the wastegate would not open so the boost would be too high. Perhaps the spring is broken or someone removed the perch?

Where is the boost gauge connected? can you be sure it is reading correctly?

[martinjs]

John, took the cap off and the spring and perch are ok, with wgfv connected it boosts to 1.5bar as it always has but drops to anywhere between 0 and 0.4bar when it gets to 5krpm.
did change wgfv btw

martin

[SteveH]

Sounds like a boost leak that's just happening under high boost. Did you check the system at Billing, with Paul's compressor and bits?

[audiman]

with that WGFV disconnected you should be able to dial in your on boost. Which spring are you using martin? I have a shcok absorber one in mine and that produces 1.2 bar with ease, with the wGFV un plugged

[martinjs]

im back with the stock spring now, i cant understand why adjusting the screw in the cap with the wgfv unplugged it didnt alter from 0.4 at all.
with it plugged in it boosted to 1.4 ish at about 3200k rpm then stay there then it just loses all boost past 5k. this cant be a leak as it pretty much holds what boost mihnea set (1.5bar, was still using 3b ic at the time)
but....
last night i removed the wg cap and tried to take the diaphram off, gave up in the end awkward to do, anyway put it back together plugged wgfv back in (spring at stock setting) and only goes to 1.1bar now but didnt cut out..what the **** is going on. wound screw down a bit and got to 1.25bar but starts playing up again.
apart from the diaphram is there anything else in the wastegate that can wear at all?
regarding the rest of the intake pipes i plugged the turbo outlet pipe,dv take off, isv take off and the pipe onto the throttle body and put 2.5bar in which it held fine.
i'll change the wg diaphram and have another go.

martin

[audiman]

Weird. I have no idea mate.

[S2central.net]

Perhaps a leak in one of the control hoses from turbo to WG via the WGFV ?

[Dr H]

Sounds a bit similar to my problem. Boosts to 1.4 bar then slowly looses it from about 2750 rpm.

With the WGFV disconnected I can't get more than 0.4 bar(ish) no matter how far I screw the srping down? I have replaced all the hoses including the control hoses to the WG and still no idea.

Mine is a definite leak, I was driving the car the the window down the other week and the noise is massive you really hear it loosing all the air - suspect something around the WG but no ideas as yet. Hope it's not a cracked ex man or something.

[Doug_RS2]

I have a spare 3B wastgate that hasn't been played with. It will fit on an ABY. I can check the diaphragm for you with a mityvac and let you borrow it to see if it makes a difference. Paul has a spare as well. Martin/Leigh? (it's isn't a light lump so will cost a few quid to post)

[Dr H]

Cheers Doug

I'm hoping to book some time with Paul N and spend a day seriously looking for the problem. We will probably change the WG then see what happens.

Paul's a busy man so not sure when yet but we'll get there

Leigh

[martinjs]

Right, ive cured the problem... for the moment anyway.
dont ask me how though.
i removed all the pre turbo pipes, wgfv pipes etc, checked them all for splits etc but they are fine , i changed them all anyway not so long ago when i swapped to aby intake system.
so put it back together used new jubillee clips (2 in some places) and doesnt cut out anymore
i think a couple of clips were possibly leaking. So i can now rev it to redline first time ive been able to do this since ive fitted this intercooler and there is definately an improvement. i'll wind the wastegate down again and see what i get.
i have a spare w/g also doug, was going to try it but dont need to now. i'll change the diaphram anyway.

i'll give it a good test tomorrow

cheers
martin

[martinjs]

i knew i'd spoken too soon,i adjusted the w/g spring to get over 1.3bar and the problem returns so i cant go above that at the moment.

this cant be fuel related at all could it?
where's mihnea?

martin

[Doug_RS2]

Mihnea is touring the US mapping lots of S4/S6 s .

You can plug in a fuel pressure gauge and drive hard to see if you get it staying at whatever your FPR is.

[martinjs]

Well i do have a 7A pressure reg, but will it need mapping if i fit this now?

martin