Boost cut

[andyg plym]

i wouldn't worth about the codes too much at this time they may have been ghost codes stored from previous tampering. fix the leak and re scan it and compare the s. you never know once the leak is resolved it may play ball.
this goes to prove my point un plugging the ecu Will not cause it to forget the faults or coding. they were still logged after it was removed.
its a bit like the myth of un plug battery to re set things!
i may be wrong on this and am by no means an expert but its my experiences with VAG cars.

Certainly an odd one eh ?
Thank you to all who have helped and been constructive !
Appreciate it as ever !!

[Monkeymagic]

Im sure it Will be sorted Andy. i bet the little drive today gave you a much needed boost. pun intended!

[newsh]

A leak at the PCV valve will be on the low pressure side so you will be sucking in some un metered air.

However..

There's a little one way valve in the PCV system hidden at the junction of 2 different size pipes down below the ISV. If this wee valve is not closing you will also be losing boost pressure and in fact recirculating boost back to MAF side of the turbo.

I would recommend removing the wee one way valve and checking it works and maybe just fitting a new one for peace of mind. You might find some of your PCV hoses are rotten too, of course the only time these get pressurised is when you do a boost leak test, this is why it's a good idea to disconnect the PCV system at the MAF hose when leak testing at more than a few psi.

I remember fixing boost leaks on my car with Martinjs back at the original garage meet in Shropsire. We fixed the last leak due to a hose clip that wasn't tightening properly, added a few more PSI and BANG blew a massive hole in the PCV pipe from the crankcase to the valve..

[andyg plym]

Thanks monkey magic and john

It was only a couple of months ago all the Pcv system was thoroughly cleaned and de clogged when I put my engine back in

We pressured the engine up and it was a huge hiss blowing out of the valve, it's about £20 from the dealers so well worth investing !

I checked Ecp and Gsf and they don't list them

[Rusty]

PCV or 1 way valve? PCV should not pressurise if you blank the breather off. Only the 1 way valve is under boost in normal operation.

[andyg plym]

We didn't blank that off only the maf hose, we didn't intend on putting that much sir in as we knew we should find the leak fairly quickly and it was a massive one coming from the underside of the throttle body hose

Obviously I appreciate that would be best etc its just I knew it would be more than a vacuum pipe

The Pcv valve must have a crack on it it was pissing out on the crown of it

[Rusty]

Was it the small bore (8mm) hose that's hidden and connects to the nipple under the IM?

By not blocking the breather, you're not testing the 1 way valve, although that wouldn't necessarily cause a boost cut if was leaking to the breather, as that's still metered air...

[andyg plym]

No it was the actual throttle hose the big one adjoining the isv

The jubilee clip had somehow slid off slightly it's a Roose hose and a bit slippy ! Looked fine from above it was the underside

[Rusty]

Sane happened on my Samco...

[driftin jo]

i wouldn't worth about the codes too much at this time they may have been ghost codes stored from previous tampering. fix the leak and re scan it and compare the s. you never know once the leak is resolved it may play ball.
this goes to prove my point un plugging the ecu Will not cause it to forget the faults or coding. they were still logged after it was removed.
its a bit like the myth of un plug battery to re set things!
i may be wrong on this and am by no means an expert but its my experiences with VAG cars.

Yes you are wrong .

http://www.s2central.net/vagcom_4.html

[andyg plym]

It's like they are greasey , again oem has the advantage with the lip on the edges

[newsh]

It's like they are greasey , again oem has the advantage with the lip on the edges

I went back to OEM on the TB hose, got fed up of the Samco blowing off.

Definitely worth buying a new one-way-valve as well Andy, it's only a few quid.

[andyg plym]

John where abouts is the valve ? Got a pic ? I would probably recognise it and yeah worth replacing

[newsh]

Sure there's a pic on here somewhere Below the ISV the hose from the PCV joins a smaller hose which connects to the IM, the step down in hose size from about 20mm to 10mm is done by the valve. The valve looks like the one under the back seat for the diff line but can't be seen as it's hidden in the hose join. Hope that makes sense!

[andyg plym]

yes i get it now,

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

on an S2 like you said John is close to the ISV