DV opening on part throttle - no N249!

[Gubien]

Hi,

I have expierenced this before, but this morning I got more into it than normal. And I really started to think about it as my car's "main" problem!.

If I start the car up from cold and get moving, when on part throttle, I sometimes hear the DV opens... like a "Wiiiiish"... If I keep my foot in that position(part throttle)... it just continues with the "wiiiiish" sound, but eventually stops... While doing that fraeaking sound, the car have a very bad acceleration...like it cant decide to accelerate or not.

I then started thinking about what could cause the DV to open, and came to a conclusion that the N249 must be doing the job.
But I then remembered, that when I had the N249 bypass, the car could do the same thing!

So, what the hell can then make the DV open under part throttle, the damn thing is supposed to be closed under acceleration as far as I know.

Unless it's the actuator that opens the flap in the turbo? But I dont know if that is a similar sound?

 

[rideonracing]

mine was doin that aswell, instead of goin tshh, it was goin ttsssshhhhhhhhhhh then stopin. i found out that it was runnin too much boost n thats why it was able to release presure under little revs!

 

[Gubien]

LOL.... That's total ironic, as mine dont want to boost properly... hmm...

How did you find a solution?

 

[w8scc]

.

try putting a spacer or two in your DV? Scott.

 

[Gubien]

I could, but the car also do it with stock boost, and that's not over 0.7 bar on mine (
Could aswell just put in the blue or red spring, but I dont assume it's the DV.

 

[ibizacupra]

dont go too stiff a spring as you will render the DV non-functional
part throttle will still have 'some' manifold vacuum.
do you have a gauge to see what level you get the noise and not?

 

[Gubien]

Ibiza cupra:

Ufortunately I dont have a gauge in the car permanently.
A yellow spring should able to hold a LCR's stock boost on part throttle? I could try a spacer, I just not sure whether this is the correct way of fixing the problem?

 

[ibizacupra]

yellow should be adequate yes.
eliminate DV out of your running issues by clamping off its vacuum pipe.. and see if it still makes a noise. If it does, then the DV is being pushed open under boost.
report back

 

[Gubien]

I will try doing that, do i need to put a plug on the vacuum pipe, or will the car not notice? (Going into limp etc?)

 

[Gubien]

Ohhh my bad, you wrote clamping...hope a strip is enough )

 

[adam cupra 20vt]

Are you saying it does this since the N249 has been bypassed?

Since fitting my FMIC mine does this but only occasionally, it only does it when your on a very light throttle and not when your accelerating hard?

I have a gauge and it does it just as the gauge starts to read boost and about 2700-3000rpm and mostly in 3rd sometimes 4th

What else could open the DV if the N249 is bypassed?

I might un do my bypass and see if it cures it although mine hardly does it at all and you have to be pretty light o the throttle for it to happen.

 

[Gubien]

Yes, it has done is with the bypass, you're correct in it very light throttle, but it continues even though I apply sligtly more pressure to the pedal.

 

[adam cupra 20vt]

Could it be because on such a light throttle the N249 would normall open the dump valve so the car would not boost?

 

[Gubien]

Dont know, thats why I'm trying to found out whether this is normal or not )

 

[ibizacupra]

Could it be because on such a light throttle the N249 would normall open the dump valve so the car would not boost?

n249 function so far as I understand is to open the DV when told by the ecu in shut down mode.. so it uses the vacuum store in the black plastic box to open the DV, even tho you may not have vacuum at the moment the ecu wants to shut things down..

eg of it shutting down on you in this manner is left foot braking

normally vacuum should pass straight thru to the DV, same as it would if plumbed direct.. but its airflow/vacuum path is via a solenoid with N249, and direct pipe without. run it direct then n249 is irrelevant.

normal operation DV see's boost and vacuum, so sealing pressure is spring pressure +manifold pressure.. or in the case of vacuum, vacuum pulls up against the spring to open. on neutral vac to boost spring pressure alone seals the Dv.

question here is does the DV open and close freely, or is there some stickign going on. you had it apart to check?

 

[Gubien]

n249 function so far as I understand is to open the DV when told by the ecu in shut down mode.. so it uses the vacuum store in the black plastic box to open the DV, even tho you may not have vacuum at the moment the ecu wants to shut things down..

eg of it shutting down on you in this manner is left foot braking

normally vacuum should pass straight thru to the DV, same as it would if plumbed direct.. but its airflow/vacuum path is via a solenoid with N249, and direct pipe without. run it direct then n249 is irrelevant.

normal operation DV see's boost and vacuum, so sealing pressure is spring pressure +manifold pressure.. or in the case of vacuum, vacuum pulls up against the spring to open. on neutral vac to boost spring pressure alone seals the Dv.

question here is does the DV open and close freely, or is there some stickign going on. you had it apart to check?

I just found out it still runs with the green spring, but clamped it anyways, and now it stopped doing it. So the green spring must be able to hold it. But the N249 must somehow get commands by ecu to open.

The Forge 007 was serviced 1000 km ago with new ring, piston etc.

 

[Gubien]

In theory it might be my actuator sticking, which could be why the high pressure is there, causing the N249 to open, but also making my car go into limp and there also not boosting properly.

But that just seems like something that bites something, that bites something i the ass... LOL

 

[adam cupra 20vt]

My DV might be sticking although I wouldnt have thought so as it was fine before I fitted my FMIC and the DV's only done about 1200 miles.

I'm not sure what it is but on very light throttle just as it comes on boost something causes the DV to open.....but not all the time

Maybe it will be sorted on my remap as I have all stage 2 mods but running standard map.

What ever it is hasn't bought up any fault codes and doesn't really bother me it would just be nice to sort it out

For the sake of connecting up 2 pipes I might re do my bypass and see what happens......I could also put the airbox back on and see if that helps.

 

[Gubien]

Had the joey of it this morning, dead cold (2 celcius) and I could just make it do it all the time... Suspecting the actuator in sticking, as this I far more noticeable on a dead cold car... which could be the reason why the ecu have to help letting out boost... but, what the feck do I know.. LOL