Hi All 

I've swapped the N75 and checked the vacuum lines, It's been suggested to me by three people that a 'clogged cat' could be the cause of the back pressure. I've spent hours on the phone but can't seem to find anyone who will come and do some tests for me. Can anyone suggest a mobile mechanic in the Sheffield area please? 

 

Pete

back to basics.  Does the actuator on the turbo move freely?  and is the connector on the MAP sensor secure?

Update...

So, I took the car to the main dealer, they performed a diagnostic and told me they couldn't find anything wrong. They suggested that it was perhaps oil in the exhaust and they should clean it out for me. They phoned back a little later and told me the turbo had failed, I took it back to the original mechanic and he has replaced the turbo through the parts warranty. I drove the car home and it drove good, plenty of power, pulled up the hill great, but blew huge amounts of blue smoke out towards the top of the hill. 

Also,

I was looking at the engine today and I noticed a cable hanging free, about 6 inches below the Vacuum pump, it has a 3 pin plug on it, the number on the plug is 1j0973703. I understand that this number is just the type of plug, but I'd like to know where it came from. The cable itself is wrapped in silver heat protection for about 14 inches of it's length. 

Any ideas?

Cheers.

There's 2 of them plugs on the engine wiring harness - no. 13 on the list in the link below

 

(im not sure if you can view it without signing up, but its free, and worth it for part catalogue tbh...)

 

http://www.vagcat.com/p/B203/971080.png

 

Does the plug thats hanging come off the loom opposite the glow plug cables, and fairly long?

Hi  mac11irl

Thanks for the link, I could see the diagram but I had to sign up to view the parts list, great site. thanks.

 

 Yes the plug thats hanging is on the loom opposite the glow plugs and is about 18 inches long with most of it covered with heat protection.

Update...

So, I took the car to the main dealer, they performed a diagnostic and told me they couldn't find anything wrong. They suggested that it was perhaps oil in the exhaust and they should clean it out for me. They phoned back a little later and told me the turbo had failed, I took it back to the original mechanic and he has replaced the turbo through the parts warranty. I drove the car home and it drove good, plenty of power, pulled up the hill great, but blew huge amounts of blue smoke out towards the top of the hill. 

That makes me wonder about valve stem oil seals, and about a re-build turbo.

The actuator will not last as long as the turbo. The diaphragm on mine went, I checked it with a vacuum pump, no response. Found an aftermarket replacement on ebay. Good as new. But if the car starts smoking, it's probably the turbo. But if you just have a lost of power and turbo pressure, it's most probably the actuator or the control valve (sits on the firewall). It will suck dust/dirt when the diaphragm goes. The actuator sits "upside down" and can collect dirt, that's why it's prone to failure.

UPDATE

 

Got over 5 litres of oil out of the sump, I noticed the level creeping up the dipstick so I dropped the oil and there was over 5 ltrs of black watery 'oil' . This oil has done just over six miles.

I suspect it could be diesel contamination and this is perhaps why the turbo kicked off in the first place.

Any thoughts please?

Leaking injector seal/seals will allow diesel to drain into your oil.

FWIW its printed on the invoice from the Skoda dealer where mine was serviced by its previous owner "we recommended replacing the turbocharger at 120,000 miles" [Nuts]

Not sure how far you can safely drive your car but if you can get it down the M1 40 miles to Nottingham, a guy called Greg Bradshaw can sort you out he has sorted more Octavia 1/Golf 4 TDis out than you can shake a stick at! He runs a garage called Nottingham Independent very trustworthy I also help him out at times as he is very busy! If interested I can give you his number?

Thanks all and thanks Octaviadan, but it's really not safe to drive. it only takes a short while to start blowing out the thick smoke and the oil is not in good condition for long - thanks anyway for the advice.