Was the only thing i could think of.
It must be the turbo going faulty im going to remove it next weekend and upgrade to a better one, dont fancy porting it to fit it and its the same.

 

There are only a few things that will cause your symptoms.

1. A split boost control pipe (you have proven its not this) ps check that there is not a leak/crack on the turbo compressor outlet nipple.
2. A blockage in the boost control system (you have proven its not this either)
3. A restiction on the actuator and/or linkage (you have proven it is not that)
4. A restriction at the wastegate port (it was my first thought but if you are sure that it has never creeped in the past then it seems unlikely to be the cause as it would have done it since the turbo was fitted).

It would be interesting to see if the plugs had caused/highlighted the issue (just going to throw this one out there ), if when the car was mapped the plugs were not operating at their best which was perhaps resulting in poor (below average) combustion, then you fit new plugs which are working at their best and offer a better combustion perhaps an increase in exhaust gas volume/speed is what has brought your boost creep issue to the surface.

Was there any noticable increase in performance when you fitted your new plugs?

Cheers Iain

 

Thanks Iain

The plugs that come out looked like there were in there for a while, it did seem to do it just after fitting new ones. ( had been very cold and snow so never really drove it hard enough to notice the boost problem or i would have put the old ones back in to try)
I wish now i had kept the old plugs, i would have put them back in just to eliminate an issue there.

I may just get the turbo off and port it, then give andy forrest a call to re map it as cant seem to find the boost issue on it.

 

Thats a good shout mate, as if for some strange reason it was the plugs masking the issue it could well have been prone to boost creep all along.

Cheers Iain

 

If your mapper reduces WG duty cycle the problem may go away.
If not you have boost creep and the WG port needs porting.

 

Just a little update on this, removed and blanked off the recirculating bov, the 1.5 map now holding boost well, still a slight increase in the 0.8 map but only a bit, looks like a faulty valve alowing boost to get into the inlet, will port the wastegate a little just too make sure tho.
Cheers
Jay

 

Well thats an odd one, a leaking DV usually results in low boost pressure and overfuelling but perhaps there is a case of the DV is letting just enough charge air out to have an effect on the overall actuator control pressure (a lower pressure would slow the actuator opening which would increase turbo output) but not enough so as to cause a huge loss of overall boost pressure resulting in your boost creep?

Keep us posted on this one mate

Cheers Iain