Boost Issues

[JonC7]

Hi all,

First of all, I have searched the forum and can't find any threads which relate to the problem I'm having.

I have a 2004 LCR 225.
When flooring it in any gear I can hear the turbo spool up as expected quickly followed by a whoosh of air which I believe is the DV (forge007p) releasing pressure.
With my foot still on the throttle this process can repeat up to 3 times before reaching the redline

I fitted a boost gauge at the weekend to help diagnose the problem, before the DV releases pressure I'm seeing 20psi!! I am pretty confident the car has not been remapped.

My 1st thought was the green spring in the DV was not strong enough however after seeing 20psi I believe that I'm getting too much pressure.

Has anyone seen this before? The engine management light is off and I've not seen any fault codes.

I've read up on the operation of the N75 valve and it sounds as though this could be causing the problems?

Does anyone have any thoughts on what I could do to prove this?
Or could it be something else?

 

[dg-1984]

The standard boost is usually between 12 and 14psi, so maybe your car has been mapped and like you said spring isn't strong enough to cope with extra boost.

 

[Ronin225]

20 psi is definitely mapped territory, the N249 sometimes make the car dump pressure if any tiny back off on throttle happened

 

[JonC7]

This problem was intermittent initially but now 9/10 times it will do it. The fact that the car didn't initially have the problem leads me to believe that its not had a remap or remap related.

I suspect the only reason I'm seeing 20psi is because the DV limits pressure to that. If I put a stronger spring in I think I'd just see more pressure before it releases.

N249 has been bypassed with no effect.

 

[Ronin225]

I cant see the car producing 20psi with out it being requested, surely this would throw it into limp mode as its half the pressure again.
The dump valve will only open and close when operated and if leaking can be re sealed
Forge do re-seal kits FOC
On the gauge does it drop pressure when you hear the noise
Which line did you tee into for the gauge, top of DV? FPR line?
Have you checked all the pipes to see if any have split or could be possibly leaking boost

 

[JonC7]

Yes, the noise occurs exactly when the gauge pressure drops.
Boost gauge is tee'd off the top of the DV.

I had a look round and the hoses seem in good order and I can hold some boost on lower throttle opening.

I don't think the DV is leaking as the problem existed before I bought the forge valve.

Does anyone know the limit at which the ECU enters limp mode?

 

[JonC7]

Update:

Fitted a new N75 valve (f / standard) to the car today and shes now running like a dream.
Boosting to 12-14psi and holding all the way.

So if anyone else has similar problems - try the N75

Thanks for the suggestions.