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Nearly 3 years since this thread was started, just lately its been the first one I look for every time I log in..
Andy it would be really easy to disconnect the hose from the WG and block the end with a 1/4" extension bar and jubillee clip. Give it some in 3rd gear, keep an eye on the boost gauge, it should easily give 1.8 Bar. If it does boost ok that would point to a boost control problem rather than a basic hardware problem.
Are you still using the MAC valve? My coupe would not give correct boost on these and I tried 2 different ones, I had to change back to a stock N75.
Just spoke to Andy, N75 first on his list. Currently he's running my unused MAC valve - we swapped it in case his was duff. We did try to get my N75 off the RS2 but abandoned that once as it was going to be a headlight out job. And it was cold and dark, and I didn't want to get stranded
Not sure about what I said about disconnecting the WG. If there is something else wrong, would it be possible to overspin the turbo trying to get to target boost?
Worth doing a couple of preliminary part throttle runs to get an impression of what it's going to do and get someone to watch the gauge like a hawk, then stop if target boost is achieved.
As long as disconnecting the N75 circuit does not muck up the fuelling, then Andy's engine is buit to take the punishment.
Cheers'en, AndyC
1994 ABY Coupe - Projekt Alpinweiss
ABY cam went in yesterday and the car hasn't started since.
Cam cover still off and it looks likes the lifters are taking their time to sit back down.
Seems strange that replacing the cam inside 30 mins has meant the lifters have unsettled to the point there isn't compression, and still after 24 hours.
Give it some in 3rd gear, keep an eye on the boost gauge, it should easily give 1.8 Bar. If it does boost ok that would point to a boost control problem rather than a basic hardware problem.
Btw, I want to clarify something about what you said.
Normally the WGDC is capped to a mapped value in the ECU.
The value is correct for a certain spring, backpressure (before the turbo) combination and a boost level.
Now, for example, if it's set at 60% in the ECU, by disconnecting the WG hose, you'd be bumping that to 100%.
So for example if it was boosting 1.6 bar before, it might boost 1.9 bar now, but it would not mean that it is a boost control problem.
When you disconnect the WG hose, even the stock little K24-7000 should instantly jump to 1.8 bar. The bigger turbos should go to 2.5 bar of boost and above almost instantly, once it spools up.
Had plenty of cars, which would be 0.2 bar shy, of what they should run, and the owners misdiagnosed the problem this way saying "but it boosts 0.2 bar more now" - it shouldn't just boost 0.2 bar more, it should boost 1 bar more at least
Considering it did not boost on Ross' ECU either, and Ross' ECU is running almost maxed DC on the N75 (he is using a standard 1.4 bar spring), that at least rules out any problems with the map or the MAP sensor.
ABY cam went in yesterday and the car hasn't started since.
Cam cover still off and it looks likes the lifters are taking their time to sit back down.
Seems strange that replacing the cam inside 30 mins has meant the lifters have unsettled to the point there isn't compression, and still after 24 hours.
What ? Do you have solid lifters or hydraulic ?? If you have solids you do realise you need to set the valve clearances with lash caps if you change the cam, if not the valves could be off there seats !
If you have hydraulic tappets then there is one other scenario and I have only ever heard of this once before, I friend of mine removed an oil pressure release valve to clean and check it and when he put it back he put it in backwards, the result was the car would start but the oil pressure was so high that it pumped up the hydrolic tappets until they started to lift the valves off there seats causing loss of compression, it took ages to figure out what was going on as when you compression tested it it was fine as there was not an excess of oil pressure but when the engine was running it would loose compression and run like a pig.
The car is running on stock ABY cams again, but unfortunately by the time the car started there is 4" of snow on the ground, not ideal for testing 1.8 bar on country lanes with summer tyres
Currently snowed in up in Cumbria lol, was meant to be returning today.
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Just spoke to Andy, N75 first on his list. Currently he's running my unused MAC valve - we swapped it in case his was duff. We did try to get my N75 off the RS2 but abandoned that once as it was going to be a headlight out job. And it was cold and dark, and I didn't want to get stranded 
given my luck that would end badly!
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