Here we go again :(

[AUDIS2avant]

So today, the problems started again.
After i bought a new MAF-sensor the car ran great for a while, no problems on idle or part throttle anymore.
So today i was out and got to race my friends 300bhp cossie, and in mid 2. gear the car startet to cut out, like it simply shut down and shortly after turned on again, half a second between.
It only does this on full throttle now
Any ideas?

running on 97ron, homefries, no boost leaks (have checked it), new MAF-sensor cam and cranck sensor, universal lambda-sensor and mfts.

any ideas??

[AUDIS2avant]

A little video :

http://s158.photobucket.com/albums/t101/cossiemanden/?action=view&current=MOV00435.flv

[Jonas_R]

Did you get the fault codes read out?

[AUDIS2avant]

not this time?
why?

[Jonas_R]

Just a general question, perhaps there was something to help out.

[AUDIS2avant]

would be nice if there was some errors tho, but am starting to think that it´s an ecu error.
Will try to put std chips inside tomorrow

[S2central.net]

Sounds like an air leak - unmetered air causing overboost alarm - STD software is even more sensitive to that.

Things like split DV or WG diaphragm will do that... Or even splits in narrow boost hose control lines.

[Jonas_R]

It could also be a leaking o-ring between intercooler and x-member. What did you use to pressure test the hoses? Just looking at them wont do the trick

[AUDIS2avant]

Jonas: im using a custom cooler and piping, and have narrow inspected all hosos.

s2central : when you say air leak, do you mean hose from maf to turbo or vacum hoses??

It does this under full acc @ arround 4500rpm-5000rpm and arr 1,2bar off boost

[Jonas_R]

I would say that you can't inspect the hose with your eyes.

You should pressure test the hoses from turbo outlet on compressor side and to the throttle body to see if it is leaking.

Also test or change the reinforced hoses that goes from turbo to N75, and to wastegate.

Also test or change all the small vacuum hoses since they see boost as well.

If you have the battery under the back seat, then have a look at the hose going to the rear diff. It is a hard plastic line that crosses over the battery, and that hose tends to get perforated perhaps due to the battery vapors or something. Before the plastic line crosses the battery it it connected to a one-way valve that insures that the diff wont see boost however this valve seems to fail as well.

If you want I have some bungs that you can borrow to pressure test with.

[AUDIS2avant]

jonas: i would like to borrow the test kit you have?
And will try to change all the vacum hoses today also, hope this helps

[Jonas_R]

Are you by any chance living close to Værløse? I'm working on my s2 for a little while or I could drive by you with if you aint that far away?

[AUDIS2avant]

Have finally arrived home after visiting jonas and some work after that, and we found the fault today
Car was overboosting cause of a split plastic-peace on the new nj75 wgfv so it couldent controle the boost
New one put in, reset the faultcodes and some testdriving later the car runs like a peach
Big up to jonas for the help

[Jonas_R]

Your welcome, glad it worked out