Why Would It Do This?

[A3 T]

For some reason while driving along at a steady speed (not fast) I hear the car dump the boost (not that there should be much boost to dump at this speed).

Also sometimes while accelerating from a stop I hear the turbo start to spool up and then the boost gets dumpped and the turbo just spools up again.



Any ideas what this could be (n75 maybe) ?

 

[A3 T]

Anyone ?

 

[cammage08]

Have you bypassed the n249? This little monkey will dump boost lile this if something is wrong...

 

[<tuffty/>]

Sounds like its going into limp mode... you need to scan for fault codes in the first instance and post them up

<tuffty/>

 

[JudderMan]

I found a small hole in my TIP that is causing something similar. Friggin £100 worth of pipe that has been rubbing on a jubilee clip which I hadn't noticed. Gutted. (N249 delete too btw).

 

[david7m]

I found a small hole in my TIP that is causing something similar. Friggin £100 worth of pipe that has been rubbing on a jubilee clip which I hadn't noticed. Gutted. (N249 delete too btw).

Silicon plus a few wraps of black duct tape? Cheap bodge until a used one comes up

Dave

 

[JudderMan]

Silicon plus a few wraps of black duct tape? Cheap bodge until a used one comes up

Dave

Well....I am from Newcastle....pikey bodge jobs are my forte

 

[A3 T]

Thanks for all the replies ;-)

I've already done the n249 bypass (as shown in my sig) and I'm not getting any fault codes.

Its also not going in to limp mode as it spools straight back up.

Let me try and explain it a bit better..

If you was to watch the boost gauge then at idle it would sit at -20, as soon as I start to pull away (smoothly not putting my foot down) the turbo quickly spools up and the boost gauge gets to about 0 then the boost dumps and the turbo spools up as it should at a normal pace.

Could this be the n75 causing boost surge?

 

[Lavis89]

I've had exactly the same problem for a long long time, a few people have mentioned having the same thing on VAG talk as well. No leaks, had it smoke tested a few times, no codes, took a trip up to bills and got it remapped and everything was fine when he scanned and smoked it, still happens, think it's always happened since i've owned the car

 

[JudderMan]

Could it be your Bailey dump valve? Can you try an OEM one to check? Sorry I can't help with the N75 thing I still don't fully understand what it does/how it works.

 

[A3 T]

I've tried the standard valve but it didn't make any difference (I've got a forge one on there now).

Another thing I've noticed that's probably not related is that sometimes if I put my foot down it feels like its lacking power, almost like I've got it in the wrong gear.