Boost Gauge Question
Page 1 of 2 12 LastLast
Results 1 to 15 of 20

This is a discussion on Boost Gauge Question within the Interior Mods forums, part of the Tech & Modifying & General Repairs category; Hi Guys, Sorry if I'm posting this in the wrong spot, but I have a question about how to read ...

  1. #1
    Registered User Major25's Avatar
    Join Date
    Apr 2012
    Location
    New Hampshire
    Posts
    30

    Boost Gauge Question

    Hi Guys,

    Sorry if I'm posting this in the wrong spot, but I have a question about how to read my turbo boost gauge. I just bought a 2012 WRX and had the dealership install the boost gauge. I read online to expect about 14 PSI from the turbo. Typically the needle of the gauge hangs straight down (reference the image below) unless I give it some gas, then it starts to rotate clockwise.

    If I push the car I can get the needle up to between the 0 and the 5, but no more than that. Should I be seeing the needle read up to 14 PSI, or am I misunderstanding something? All the values it hits on its way to zero, are those negative pressure values?

    Sorry again for my ignorance, but I can't seem to figure it out. Thanks for any help you can give!

    Click image for larger version. 

Name:	2009-spt-boost-gauge-subaru-sti-wrx.jpg 
Views:	160 
Size:	158.1 KB 
ID:	104576

  2. Remove Advertisements
    ClubWRX.net
    Advertisements
     

  3. #2
    Registered User JaySin's Avatar
    Join Date
    Mar 2008
    Location
    SE Michigan
    Posts
    375
    The negative is (inches of mercury I believe) vacuum pressure. That's where it will be when you're cruising or off the gas generally. It will vary. You're not going to hit 14PSI (or whatever your peak boost is) just any time you're hitting the gas...only at certain engine RPMs and in certain gears. The best way to see it peak is maybe cruising on the highway in 4th or 5th at around 60-70mph...then floor it briefly. It'll use more boost and you'll see it spin up more.

  4. #3
    Pro Manscaper Mikie13's Avatar
    Join Date
    Oct 2006
    Location
    Palmyra, NJ
    Posts
    20,981
    Below zero is vacuum (where the intake manifold reads negative pressure). Above zero is boost, in PSI. Stock boost in WRXs is just below 14PSI, so my guess is the gauge is reading wrong. You won't get to positive pressure until you start accelerating relatively harder, otherwise it stays in vacuum.

    If you go WOT, you should hit close to the 14 under load (2nd, 3rd gear). Where is the gauge pointing when the car is off, but ignition turned on to accessory?
    The Hawk-Eye Alliance #90|The Blobeye Syndicate #0|The Stink-Eye Mob #0|N.E.R.D. Founding Member & #3
    2012 Lightning Red WRX Sedan
    Stock...for now Soon to be OpenSource tuned by: Mattypants @ WTF Tuning

  5. #4
    Admiral Ackbar the 1st mycologist's Avatar
    Join Date
    Oct 2005
    Location
    Late Devonian
    Posts
    13,214
    I Support ClubWRX
    Or very likely the car is running on wastegate spring pressure and not making full boost.

    In addition to Mikie's good question, what is it reading for vacuum at warm idle? Where is it T-d in (how is it installed)?
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

  6. #5
    Registered User JaySin's Avatar
    Join Date
    Mar 2008
    Location
    SE Michigan
    Posts
    375
    OK, no offense, because this is all smart and legit so far, but do you guys REALLY think that his brand new 2012 WRX has boost issues already? I just kind of assumed (silly me?) that he wasn't sure what he was looking at and it was that simple. Call me crazy...

  7. #6

  8. #7
    Admiral Ackbar the 1st mycologist's Avatar
    Join Date
    Oct 2005
    Location
    Late Devonian
    Posts
    13,214
    I Support ClubWRX
    Actually, I never stopped to check what year. But yes, though less likely.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

  9. #8
    Pro Manscaper Mikie13's Avatar
    Join Date
    Oct 2006
    Location
    Palmyra, NJ
    Posts
    20,981
    Quote Originally Posted by JaySin View Post
    OK, no offense, because this is all smart and legit so far, but do you guys REALLY think that his brand new 2012 WRX has boost issues already? I just kind of assumed (silly me?) that he wasn't sure what he was looking at and it was that simple. Call me crazy...
    I too doubt it has boost issues, but...it could have Boost Gauge issues. These new SPT gauges actually do not have a good reputation for working correctly or being accurate. Plus, if they were T'd in wrong to the lines or in an incorrect place, it could cause further issues (or even CAUSE a boost issue).

    Quote Originally Posted by brew04 View Post
    Still in the break in period, it would probably be best not to see 14 psi yet.
    A few WOT pulls to make sure it is in fact boosting correctly won't hurt it. As long as you are doing your majority of driving within breakin specs, you're fine. But think it...you should make sure that it's going to run like it's supposed to. Better to find a problem sooner than later.
    The Hawk-Eye Alliance #90|The Blobeye Syndicate #0|The Stink-Eye Mob #0|N.E.R.D. Founding Member & #3
    2012 Lightning Red WRX Sedan
    Stock...for now Soon to be OpenSource tuned by: Mattypants @ WTF Tuning

  10. #9
    Registered User Major25's Avatar
    Join Date
    Apr 2012
    Location
    New Hampshire
    Posts
    30
    Thanks for your input guys. I'm leaving work now, I'll get back to you about where it's sitting both when the car is turned to accessory, and when it's at warm idle.

    What do you mean by WOT pulls?

    It just makes me think something is wrong because the couple of times I've pushed it in 2nd or 3rd, the most I've seen the gauge read is between 0 and 5.

    *edit: By "push it", I mean almost hit red-line.

  11. #10
    Registered User peekeesh's Avatar
    Join Date
    Mar 2012
    Posts
    67
    ^^ WOT means wide open throttle

    I've seen my car hit 14psi on 3rd gear with gas pedal half pressed. my car is new and has 500 miles i use prosport gauge though.

  12. #11
    Registered User Major25's Avatar
    Join Date
    Apr 2012
    Location
    New Hampshire
    Posts
    30
    Yea that doesn't sound anything like mine. WOT in 3'rd only gets me just above zero.

    At a warm idle, the needle is pointing straight down in the middle of the word 'boost' on the gauge.

    When the car's electronics are turned to accessory, the needle is pointing to -24 (inches of mercury?)

    Based on what I'm hearing from you guys, this doesn't seem right..but what do you guys think? Is it something I should go get checked out at the dealer?

  13. #12
    Registered User peekeesh's Avatar
    Join Date
    Mar 2012
    Posts
    67
    maybe the gauge itself is defective. mine at idle sits around 21-25. Better take it to the dealership and have them check it.

  14. #13
    Admiral Ackbar the 1st mycologist's Avatar
    Join Date
    Oct 2005
    Location
    Late Devonian
    Posts
    13,214
    I Support ClubWRX
    Is there a calibration function?

    Personally I'd take that junk back and get a refund.

    EDIT:
    http://www.daddysscp.com/Ultra_Basic...52bst-amwh.htm
    Last edited by mycologist; 05-02-2012 at 03:07 PM.
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

  15. #14
    Registered User Ingo's Avatar
    Join Date
    Mar 2012
    Location
    Colorado Springs, CO
    Posts
    1,110
    Gotta chime in here: at ingition on with the engine not running the intake pressure HAS to be 0 (zero) !
    If it's not the gauge is just junk, or wired wrong,or off-calibration, or... take your pick....

    So, the picture in the original post is with the engine running in idle?
    You can't have everything - where would you put it?

  16. #15
    Admiral Ackbar the 1st mycologist's Avatar
    Join Date
    Oct 2005
    Location
    Late Devonian
    Posts
    13,214
    I Support ClubWRX
    Quote Originally Posted by Ingo View Post
    Gotta chime in here: at ingition on with the engine not running the intake pressure HAS to be 0 (zero) !
    If it's not the gauge is just junk, or wired wrong,or off-calibration, or... take your pick....

    Yes. And it should be right at least for sea level if you live there, and it should be calibrate-able if you live anywhere else (like the one I posted, which also matches the other gauges).
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •