ABY ECU Intermittent issue

[S2central.net]

probably a higher spec spring, but also check the WG valve itself isn't sticking... with a vacuum applied (by hand pump) to the upper chamber then quickly removed you just hear a satisfying & swift 'thunk' as the WG spring pushes the valve back down into the gate.

[twoqu]

Well for OE I get 85mm length, 2.8mm wire thickness with a 38.5mm OD.
I have also found a spring with a blue paint stripe which is 75mm length, 3mm wire thickness and 36.5mm OD which I think is from a 10V not a 20V. Due to the smaller ID it will not fit over the 20V spring perch.
With the cap inverted, the top of the perch is 25.5mm from the cap flange if thats of any use. The perch itself should be 40mm OD 32.5mm ID with a step of 5.8mm. So you would need to add 5.8mm to the 25.5mm to get a dimension from the cap flange down to where the spring seats. All the measurements are from an unmolested wastegate.

There appears to be no paint ID on this particular OE spring and the silver paint mark on the other I have might just be wishful thinking on my part. It is only what appears to be a blob of silver on one coil as opposed to a stripe down the spring.

[edge_devil]

Thanks guys, I'll try and get in tonight and nail it all down, size, sticking etc.

With a std spring do we have a lbs/inch kind of value I can use to measure spring strength as well?

[S2central.net]

I did some tests with an airline before - you might find results of that in here with a search - tis a few years old (or more)

[edge_devil]

Not feeling it... unplugged WGFV, wound screw all the way back in the WG housing, opened the WG and checked everything moved ok (not got a pump yet to check by hand) all looked good, went for a drive I get 1.4 bar of boost, ffs now that's annoying, and that is with the WGFV uncoupled. I reset the ECU, plugged in the WGFV and drove home but didn't get room to go fast enough to go past 1.0 bar.....!

For info the spring is;
81.92mm long
38.34 OD
32.81 ID
2.84 Wire thickness
Depth from lip of WG cover to spring seat, 30.19 (See photo)

[twoqu]

Here is where the fun starts!
Check for fault codes. Check the wastegate diaphram.
Out of interest where is the measurement for the gauge taken from? Does it measure vac/boost? What does it read without the vehicle running?
I think we can assume the spring is close enough bearing in mind the age of the component. If you were being a pedant than the seat could be a little lower!

[edge_devil]

Hi Robin,

The takeoff is from the same line as the fuel regulator at the top of the engine. I'm showing vacuum at idle and before the turbo spins up...I'll try and get some video footage of the gauge when I get a chance.

Still no error codes in the ECU. I did notice one of the wastegate cap mounting studs is tapped all the way through into the feed for the lower half of the valve....not an issue, just an observation.

On another note, is it possible to fit the crankcase breather valve the wrong way?

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[twoqu]

When you say you are unplugging the wgfv, you are just pulling the electrical connector off right?
I would have thought that would give you a fault code in itself.

[edge_devil]

Sorry yes, WGFV gave an error, I meant no other errors and yes just the electrical plug.


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[UrS4boy]

AAN/ABY/ADU Positive Crankcase Ventilation (PCV) System

..On another note, is it possible to fit the crankcase breather valve the wrong way?

Not sure which valve you are talking about, the one way bleeder valve or the pressure regulating valve:

http://forums.quattroworld.com/s4s6/msgs/22506.phtml

AAN diagram:

[edge_devil]

The pressure regulating valve, but based on your diagram mine is correctly installed....


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[twoqu]

Is the wgfv plummed in as follows:
Bottom port to turbo housing.
Longer port on side to intake from maf to turbo.
Shorter port on side connected to lower wastegate port.
Obviously your packaging is a little more creative than stock!
I am struggling to fathom how you are getting 1.4bar of boost on stock spring unless the wastegate is either stuck or not getting any pressure at the lower wastegate port to operate it. The wgfv should fail in a manner that still allows pressure from the turbo to operate the wastegate.

[UrS4boy]

N75 WGFV info and review of N75 options

Just to put a visual to what Robin is saying:

http://forums.quattroworld.com/s4s6/msgs/20987.phtml

[edge_devil]

I had the same thought..... Is on the list


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[edge_devil]

So I may have the WGFV round the wrong way.....



...in the picture you can see the valve with the exit towards the camera going to the hose between the turbo and the intercooler, the hose on the right going to the wastegate and the hose furthest away going to the inlet side of the turbo, between the maf and turbo...


Now with diagram... (Attachment)