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Boost Pressure Curve?
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stevebez
 


Member Since: 18 Apr 2011
Location: Kent
Posts: 87

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Ipanema SandDiscovery 4
Boost Pressure Curve?

So still trying to get my LR4 sorted after a lean condition required a full rebuild.

Engine back together and then suffered a cracked LH manifold. Back under warranty and needed new injectors (again), plus some other bits on the inlet side.

Car builds great boost under the primary turbo (~22psi) and when the secondary turbo kicks in @ 2500rpm I get a drop in boost (and a bit of a whine - Leak? Turbo?) but eventually it gets back up to 22 Psi. Weirdly the wine seems to be dependent on which gear I am in, as does the drop in boost. (e.g. 3rd gear do not notice it much boost drop .. when you transition quickly through 2500 rpm (2nd gear) it seems the boost management cant quite keep up with the engine speed)

I am going to check secondary turbo piping for leaks and do the oil return mod. I also heard the gaskets on the secondary turbo could need attention potentially.

That said car pulls really well now ... the boost gap is annoying ...

So 2 questions...

How seamless should the boost transition be around 2500 when the 2nd turbo is active? My drop is around 4-5 psi (22->17/18 in 2nd gear) and then building again from there.

Is there a way to reset the adaptations for this?

I cant wait to get this last bit solved so I can get rid of this car. Anyone want it? 2012 79k miles
  
Post #231304730th Oct 2022 5:32 pm
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Disco_Mikey
 


Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20842

Scotland 2005 Discovery 3 TDV6 HSE Auto Cairns BlueDiscovery 3

The transition between primary and secondary turbo is noticeable, especially noticeable if accelerating and using the paddle shift to change up

Haven't ever graphed it, but I do expect the figures you are seeing are *probably* normal
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Post #231305830th Oct 2022 7:04 pm
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stevebez
 


Member Since: 18 Apr 2011
Location: Kent
Posts: 87

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Ipanema SandDiscovery 4

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Post #231313731st Oct 2022 8:03 pm
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