P0234 code overboost ctt

[lewisweller 77]

Err well here it is the first code to pop on the problematic ctt P0234 overboost. Was driving to today and booted it a bit and felt flat to redline Wtf, almost like the variocam didn't switch to high lift because the boost gauge said +0.8 bar still as per spec. So I whipped out the trusty v-checker which is always in the temperamental Pig in case, and it shows the P0234 code. 

I know the possible causes and have read a lot of posts of this code but not found any with fixes except loose piping broken piping which at the moment I'm thinking I don't have any (all bloody new). N75 valve is new, MAP sensor is original but I've cleaned it today and before it didn't make any difference then or now. Turbo problem possible but unlikely I think. So what does that leave?  

 

If I clear codes it won't return in short run but did after many Km today return and cleared again. 

 

No here is the only interesting thing about it, when the code is active it goes into a limp mode flat performance and the stutter hesitation I suffer with since I got the car goes away and it drive smooth but slower of course. I clear the code and get boost back but also the kangaroo stutter stammer acceleration. 

 

If I disconnect the map sensor exactly same result but a difference code like P???? Underboost which makes sense. 

 

So guys what makes a turbo engine do this? 

[ekstroemtj 25]

Looks like you are on the same point now like i am.

[lewisweller 77]

This was an easy fix thank goodness. Found the little bit of connecting tube to the bottom of the n75 valve is split open (this is the positive boost reference from the passenger side turbo for the n75 valve used to open the wastegates hence overboost cos it can't open the wastegates without air pressure), I cut the pipe shorter to avoid it squashing the soft as sh*t pipe in the future. No codes now. Still stuttering lol POS pig.