wont hold boost

[chris.baldwin]

Hey guys,

Got myself another cupra yesterday, on the way home I gave it some beans, boosted to 15/19psi which I was expecting, but I then started to tease it, by that I mean slowly increase the boost till I floor it was holding around 8psi then would dump, would hold 8 again then dump, without me taking my foot off the throttle...

Any suggestions, boost leak?

Cheers,
Chris.

 

[AlexGSi2000]

N75 Valve is the most likely culprit.

 

[chris.baldwin]

Had an n75 bypass apparently...

 

[Chambers_CUPRA]

Has it got a mbc then?

 

[chris.baldwin]

I haven't had a chance to properly look at anything. It's just winding me up that it just boosts, then drops then spools again!

 

[chris.baldwin]

right well I've replaced the N75 valve to no avail, still doing the same bloody thing. Any other suggestions people?

 

[denzil691]

map sensor or boost leak i reckon

 

[chris.baldwin]

See I thought boost leak but it holds 1.5bar when I've got my foot planted, it just pisses around when I'm spooling...

 

[Danturbo225]

What Ibiza did u get?
Any pics?

 

[T1200Y]

I had a similar problem, couldn't find a boost leak anywhere , then I decided to go for the k03s turbo change and noticed when I took the old turbo off I turned it around and realised there was a hair line split on the bit of cast iron that bolts from the turbo to the downpipe.. It's holding nicely now