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Old 06-19-2017, 02:10 PM   #1
BOL3RO
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Default 2016 Wrx Idle Boost Reading

Hey! Probably a newbie question for many but I can't seem to find a simple and direct answer anywhere.

As the car sits in idle, the Subaru boost gauge reads between -7 to -8 Psi most of the time in "D" (CVT transmission). In "P" it'll typically sit between -8 to -9 Psi. Please advise wether or not this is normal.

Info: 2016 WRX CVT, Cobb big sf intake system / 91oct stage 1+ map.

Thanks!
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Old 06-19-2017, 02:16 PM   #2
david211
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Normal as in the negative numbers or normal as in those specific readings?
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Old 06-19-2017, 02:17 PM   #3
BOL3RO
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Originally Posted by david211 View Post
Normal as in the negative numbers or normal as in those specific readings?


Thanks for the reply. The specific numbers.
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Old 06-19-2017, 02:20 PM   #4
david211
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I would say that that is normal, every car is different and numbers will fluctuate but I wouldn't worry about it. Mine (granted it is a 6 speed, which shouldn't matter that much) idles around the same on a "Stage 2" Etune.
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Old 06-19-2017, 02:25 PM   #5
BOL3RO
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Originally Posted by david211 View Post
I would say that that is normal, every car is different and numbers will fluctuate but I wouldn't worry about it. Mine (granted it is a 6 speed, which shouldn't matter that much) idles around the same on a "Stage 2" Etune.


Thank you! When I purchased the wrx in march the climate was cool/cold with an average reading of -9psi in "D". I was also curious if current summer climate would contribute to the subtle difference at all.
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Old 06-19-2017, 02:45 PM   #6
david211
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Default 2016 Wrx Idle Boost Reading

Quote:
Originally Posted by BOL3RO View Post
Thank you! When I purchased the wrx in march the climate was cool/cold with an average reading of -9psi in "D". I was also curious if current summer climate would contribute to the subtle difference at all.
No problem!

The ECU has a wastegate duty cycle Intake Air Temperature compensation table (WGDC IAT) that pulls WGDC based on the intake air temperature. It starts pulling WGDC around 40 degrees ambient, so you will start underboosting in cold temperatures if the tune wasn't adjusted for this.
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Old 06-19-2017, 02:50 PM   #7
BOL3RO
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Originally Posted by david211 View Post
No problem!

The ECU has a wastegate duty cycle Intake Air Temperature compensation table (WGDC IAT) that pulls WGDC based on the intake air temperature. It starts pulling WGDC around 40 degrees ambient, so you will start underboosting in cold temperatures if the tune wasn't adjusted for this.


Ahh, ok. The subtle increase in a warmer climate makes sense now.
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Old 06-19-2017, 07:09 PM   #8
rich3389
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Quote:
Originally Posted by david211 View Post
No problem!

The ECU has a wastegate duty cycle Intake Air Temperature compensation table (WGDC IAT) that pulls WGDC based on the intake air temperature. It starts pulling WGDC around 40 degrees ambient, so you will start underboosting in cold temperatures if the tune wasn't adjusted for this.
This has nothing to do with idle.
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Old 06-19-2017, 08:08 PM   #9
NewToThisWRXThing
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My 2016 WRX idles at around -7 psi. Does this mean it's restricting airflow into the engine as opposed to when the psi is positive and pushing more air in?
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Old 06-19-2017, 08:20 PM   #10
GlarryHoodDIT
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No, it means your engine is taking in air, but not compressed air from the turbo. The air is still passing through from the intake through yhe turbo and into your manifold, but the turbine isnt spinning so the air isnt compressed and thus more powerful.
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Old 06-19-2017, 08:54 PM   #11
tramp
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Turn the A/C on at highway speeds and watch it change.
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Old 06-20-2017, 10:10 AM   #12
Loyale93
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Call your dealer with new car questions.
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Old 06-20-2017, 10:24 AM   #13
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Isn't there a bit more drag on the motor in D vs. P? That would explain the slight reduction in vacuum?
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Old 06-20-2017, 10:26 AM   #14
SoapBox
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Quote:
Originally Posted by Loyale93 View Post
Call your dealer with new car questions.

You could use that as an answer to 1/2 the threads started on here. No one would be getting any help from your average dealership worker anyway...generally clueless.
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Old 06-20-2017, 10:30 AM   #15
SoapBox
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Quote:
Originally Posted by GlarryHoodDIT View Post
but the turbine isnt spinning so the air isnt compressed and thus more powerful.
Even at idle, the turbine is certainly spinning, might even be several thousand RPMs.
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Old 06-20-2017, 10:47 AM   #16
GlarryHoodDIT
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Sorry, spinning but not building boost.

Quote:
Originally Posted by SoapBox View Post
You could use that as an answer to 1/2 the threads started on here. No one would be getting any help from your average dealership worker anyway...generally clueless.
Tgis from the guy who posts "stop buying ejs thats ur problem lololol" in lile 8/10 threads?
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