Boost issues.

[Jas11n]

Thanks Fitzy

Hmmm there's a bit of a rabbit away here me thinks

[FITZY]

When I give mine a quick sharp flick of the throttle pulley when stationary, mine clicks away like a good un'. Does have to be quite a 'hard' rev though if you get what I mean.
HTH

[Jas11n]

Bump.
Need to be able to cross this anomaly off the list.
Which is correct? If I rev the engine, should I be able to feel the valve clicking or not at all?

[Jas11n]

One thing about the WGFV has puzzled me though.
The original valve was click-clicking away fine when running output test mode in vag-com.
If you held your hand on it and revved the engine, you could feel it clicking away like mad.

The new WGFV clicks away just the same when in output test mode, but does not click when revving the engine as above.

Why is that?

[Jas11n]

Only other thing I am thinking about here is that your WG might actually be stuck open....

When the WG cap is on and you applied vacuum - sucking the valve upwards - did you hear a nice 'thunk' as the WG spring closed the valve when you removed vacuum ?

Does the valve move nice and freely when you have the WG cap off ?

The car was down at my local specialists when the wastegate diaphram was tested. They had a handheld vacuum thing (mitivac?) and said it held it's vacuum.
They didn't however comment on the being able to tell if the valve was ok.
I'll whip the cap off tomorrow morning and see if it operates smoothly.

Thanks for the pointers, this is new territory for me having never had anything remotely like this in the 5.5 years I've had her.
I'll nail it eventually

Thanks to Andy for the loan of the 1.9bar spring too

[s2_bo]

Good call Paul, maybe that's it......

[S2central.net]

Only other thing I am thinking about here is that your WG might actually be stuck open....

When the WG cap is on and you applied vacuum - sucking the valve upwards - did you hear a nice 'thunk' as the WG spring closed the valve when you removed vacuum ?

Does the valve move nice and freely when you have the WG cap off ?

[S2central.net]

You can try a couple of bodges here...

1 - The big 1.9bar spring and disconnect WGFV - this will provide max boost of 0.9bar - safe to the redline on K24

2 - Keep factory spring and bodge the WGFV to be active all the time (apply 12V across it) - forces the turbo to keep boosting until EXHAUST manifold pressure cracks the WGFV open... Not at all elegant and you'd need to keep a close eye on boost levels to run like this - actually the ECU might throw toys out of the pram before you get into any dangerous territory. Never BTDT on this one.

[AndyP]

The uprated spring drops straight in, no mods req'd. It's the same size as the std spring, just a lot stronger. I have a 1.2bar one too if your not feeling brave!

[Jas11n]

Unplug the WGFV and put a 1.9bar spring in the wastegate, that'll force it to boost I have one you can borrow if you want, at your own risk obviously!

That'll mean butchering the wastegate cap wouldn't it Andy?
I'm not wanting to leave it like this obviously, just wanting to confirm the the turbo itself isn't dead.
I thought, unhook the hose from the WGFV that goes to the coldside and bung it. Hook a hose up direct from the maf hose to the lower port of the wastegate.
Assuming the turbo ain't tit's up, I should get more than 0.4bar of boost, although it'll be boosting full on before WOT

Sound right?

[AndyP]

Replaced front knock sensor with a new one, still no boost above 0.4bar.
In fact, she'll not boost beyond 0.2bar most of the time.

I'm at a loss now. I've changed everything possible bar taking the engine out and giving it a good kicking

Is there any way I can "briefly" force it to boost to rule out maybe damaged hotside blades of the wheel . I don't fancy taking the turbo off just yet if there's an easier way first.

Unplug the WGFV and put a 1.9bar spring in the wastegate, that'll force it to boost I have one you can borrow if you want, at your own risk obviously!

[Jas11n]

Cheers Bo, maddening aren't they

Have I got this right in my head?
The lower port of the wastegate is presented with vacuum from the maf hose to keep the wastegate closed beyond spring pressure. When appropriate, the WGFV switches the feed to the pressurised air from the port on the coldside of the turbo to force open the wastegate??

[s2_bo]

What a pisser! sorry to hear this Jas, nothing worse then poring money in to the car with no change.

I did that on my rs2. Replaced all the wheel bearings one by one to try and stop the sound but it turned out to be the brakes sticking.!

Best of luck !!

[Jas11n]

Replaced front knock sensor with a new one, still no boost above 0.4bar.
In fact, she'll not boost beyond 0.2bar most of the time.

I'm at a loss now. I've changed everything possible bar taking the engine out and giving it a good kicking

Is there any way I can "briefly" force it to boost to rule out maybe damaged hotside blades of the wheel . I don't fancy taking the turbo off just yet if there's an easier way first.

[Jas11n]

Is it sorted ??

Just about to update this Alastair.

In a word................nope

In addition to the above, I've had both cats off to see if maybe the matrix had broken up blocking the exhaust, but they are fine. I've replaced the rear knock sensor to no avail. Hopefully this afternoon I can get on and replace the front knock sensor, which is a bit of a pain to get to, but I've got the top rear rad hose to replace with a new one, so should give me a few more nano-millimetres to play with
The wiring to the WGFV is fine, it's been buzzed from the ECU with lots of wiggling and so on to see if it could have had an internal break in either of it's two wires.

The wastegate diaphram has had vacuum applied to the top and it holds that vacuum fine, so it's not split.

I've taken to calling her the "Byzanz Bitch" at the minute. Allie (GF) reckons she's in the huff as I use the TDi more.
I would care, she's driving brilliantly apart from this no boost issue. Had the clutch master cylinder changed yesterday cos that pesky rod bent and the pedal was getting REALLY stiff and sticking down at times.

I 'may' end up having to drive down country to see someone like Tom or Doug. The corner I'm in is getting a bit claustrophobic

Forgot to add.
In not wanting to overlook the obvious, I've had the hose off the coldside inlet of the turbo, and the wheel spins freely and doesn't have any excess movement either side to side or in and out.