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Is this manifold air pressure graph normal?
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pronvit
 


Member Since: 27 Jan 2020
Location: AKL
Posts: 7

New Zealand 2006 Discovery 3 TDV6 HSE Auto Unknown ColourDiscovery 3
Is this manifold air pressure graph normal?

See the screenshot. When I press accelerator (just in neutral, up to about 2500rpm), manifold pressure goes down, then rises when the turbo kicks in. Is this normal?

(Don't ask me why values on the pressure axis are wrong. Also, is boost pressure actuator data not available normal?)


Click image to enlarge
  
Post #220701131st Jan 2021 9:37 pm
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sarumlight
 


Member Since: 07 Nov 2008
Location: Off the Plain
Posts: 1591

United Kingdom 2008 Discovery 3 TDV6 HSE Auto Tonga GreenDiscovery 3

Sounds normal to me. In a normally aspirated engine the manifold always has a vacuum. With a turbo, you press the pedal, adding fuel, and the engine speeds up and sucks more air out. Then the turbo spins up and starts shoving more air in so the pressure goes up.  
Post #220701231st Jan 2021 9:47 pm
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pronvit
 


Member Since: 27 Jan 2020
Location: AKL
Posts: 7

New Zealand 2006 Discovery 3 TDV6 HSE Auto Unknown ColourDiscovery 3

Yeah that surely makes sense, it's just I found this topic with a similar graph before measuring mine: https://www.disco3.co.uk/forum/post1953278.html#1953278

I don't see the pressure going down there - neither when throttle angle rises nor actually at all lower than the idle value.  
Post #220701631st Jan 2021 9:53 pm
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pronvit
 


Member Since: 27 Jan 2020
Location: AKL
Posts: 7

New Zealand 2006 Discovery 3 TDV6 HSE Auto Unknown ColourDiscovery 3

Ok looks like this is only when in neutral, when driving it’s all good. Sorry I couldn’t drive it at that moment to check myself.  
Post #22070551st Feb 2021 3:07 am
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