strange boost fault

Ovid

Ovid

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Im pretty sure this is a DV issue but any help appreciated.

1.8t under WOT 2nd gear going uphill and the boost comes in , then it drops off and then comes back, this happens all the way up to about 6k revs, DV or N75 folks ?
 
Get it scanned .. Should show up on there
 
Scanned it but not showing anything , which is weird , thinking diaphragm in dv has gone.
 
Take it off and blow in it should only let air out one way
 
Booted it up the hill again , fault still same only code is
16804 - Catalyst System; Bank 1: Efficiency Below Threshold

No leaks and sensors working ok so going to get to DV and check out vacuum feed and valve next.
 
Could be lamba probe then if it's saying bank one
 
audi upgrades
Well i cleared the fault , booted it again and turbo still pulsing but fault code has not come back.
 
I have this same code and same prob on my 1.8t only since I had a new turbo I also get fuel system to lean bank one that I belive is a lamba sensor I'm going to get a decat very soon see if that helps as only had these codes sine I had the middle box delete on my stainless system
 
Check vacuum line to dv and dv itself, ive not got round to it yet but it has to be 1 of them or the N75 boost control valve but normally that throws its own code.
 
I've got the same Issue, no code, but Boost hesitating/surging,

I noted a number of connections had been replaced with Jubilee clips so i took them all off to check pipes for splits, didn't see any until i took the jubilee clip that clamped the main hose from the intake to the turbo inlet off the pipe to reverse it, there doesn't seem to be too many orientations that a Jubilee can sit in nicely around the Turbo inlet and this time it had been put on wonky and there was a two inch split underneath, my next plan is to replace this main intake hose (not sure of its proper name)

If that solves it i'll let you know!
 
Turned out to be related to the old cam chain tensioner being knackered which controls variable valve timing, new chain and tensioner . no rattle no surging nothing its perfect now.
 
How did you make the connection to the tensioner having gone? and is there an easy way to diagnose if it's gone once you get access to it?
 
You get a nasty rattle when engines up to temp which goes off once oil pressure up, also you can get from engine on cold start and sometimes you get cam crank correlation dtc
 
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