Overboosting?
Results 1 to 13 of 13

This is a discussion on Overboosting? within the Tuning: Electronic Engine Management forums, part of the Tech & Modifying & General Repairs category; So first of all, my car is an 03 WRX. Completely stock except for an AccessPort flashed to Stage 1 ...

  1. #1
    Registered User Monk_Knight's Avatar
    Join Date
    Aug 2010
    Location
    Colorado
    Posts
    550

    Overboosting?

    So first of all, my car is an 03 WRX. Completely stock except for an AccessPort flashed to Stage 1 91 octane. I have the AccessPort mounted to the side of the wheel and I use it for a boost gauge.

    I was driving home tonight and accelerated pretty hard in 4th to pass someone on the highway and right as I was passing them I glanced over and saw that the AP was reading 16 psi. Later, I had to pass someone else, this time there was less room so I went to 3rd gear. The car pulled strong and smooth... felt great, but after I was around the guy, the AP said I had hit 17 psi.

    That's more than a Stage 2 WRX should be hitting, right? I thought that Stage 1 was supposed to hit 14.8 and Stage 2 was 16.5. What's up? Is this something to worry about? I was planning on putting on a downpipe and going Stage 2 in a couple days but I don't want to do that if something is wrong...

    Edit: The one thing I thought of is that I am at ~7000 feet. It's considered safe to run higher levels of boost at higher altitudes, right? Could the "learning" function of the ECU be kicking in here and upping the boost?
    Last edited by Monk_Knight; 07-30-2011 at 09:42 PM.

  2. Remove Advertisements
    ClubWRX.net
    Advertisements
     

  3. #2
    Registered User poly_poly-man's Avatar
    Join Date
    Feb 2010
    Location
    Rochester Institvte of Technorcery
    Posts
    1,223
    I can assure you that those are safe numbers, as long as they are not carried to redline. However, some datalogging would be nice, and do check the map notes.

    If there is indeed a problem, first off figure if it's new, or if the map is what caused the issue. If the latter, consider loosening the wg arm, and definitely consider upgrading to a better BCS.
    My big thread: The Used WRX Buying Checklist - Please Contribute!

    My current car: 2002 WRB WRX Wagon.
    Mods: GM BCS, Carberry SD rom, uppipe, AEM UEGO, Klunk Killer, F+R shifter bushings, head unit

  4. #3
    Registered User Monk_Knight's Avatar
    Join Date
    Aug 2010
    Location
    Colorado
    Posts
    550
    What do you mean, if they are not carried to redline? When I hit 17 psi I was close to redline in 3rd gear, though I don't think it hit that and stayed there... more that it hit that at the peak point before I shifted to 4th.

  5. #4
    Registered User poly_poly-man's Avatar
    Join Date
    Feb 2010
    Location
    Rochester Institvte of Technorcery
    Posts
    1,223
    the td04 is safe (and I mean SAFE) to about 20-21psi in the midrange (roundabout 4-5k, but you should do the math with the turbo map), as long as you taper to more like 11psi by redline.

    regardless, if you're hitting boost beyond your target, get it fixed. You can always up your targets later.
    My big thread: The Used WRX Buying Checklist - Please Contribute!

    My current car: 2002 WRB WRX Wagon.
    Mods: GM BCS, Carberry SD rom, uppipe, AEM UEGO, Klunk Killer, F+R shifter bushings, head unit

  6. #5
    Moderator Donkey's Avatar
    Join Date
    Apr 2005
    Location
    Da boonies
    Posts
    6,036
    I Support ClubWRX
    Your probably just getting a brief boost spike. Learn to use the datalogging feature on the AP
    Resident Adviser @ WTF Tuning, LLC
    2002 FORESTER S
    1998 FORESTER S




  7. #6
    Registered User Monk_Knight's Avatar
    Join Date
    Aug 2010
    Location
    Colorado
    Posts
    550
    And this brief boost spike is okay? I'll try to get a data log from the AP today, but I don't really know what I am looking for in the data except maybe what RPM the boost goes higher than expected.

    The big question for me right now is I am supposed to get a downpipe put on tomorrow and go Stage 2. Then the next day I'm driving 1000 miles to school. Is this an issue I should be worried about?

  8. #7
    Moderator Donkey's Avatar
    Join Date
    Apr 2005
    Location
    Da boonies
    Posts
    6,036
    I Support ClubWRX
    No.
    Resident Adviser @ WTF Tuning, LLC
    2002 FORESTER S
    1998 FORESTER S




  9. #8
    Registered User Monk_Knight's Avatar
    Join Date
    Aug 2010
    Location
    Colorado
    Posts
    550
    Ok thanks.

    I went out just now to try to get some data logs from the AP, but it didn't seem to want to go into logging mode. I would choose data log, it would pop up some short instructions and say to hit ok to begin logging. I would do that and it would just go into normal gauge mode and it clearly said "not logging" on the screen. I checked to see that the parameters of the data logging mode were set right and they were.

    Oh well, not too concerned about that right now. I just kept an eye on it and drove around. I gave it two hard pulls in 3rd. The first time it peaked at low to mid 15's and then tapered down to around 11psi near redline. The second time it hit 14.9 and stayed there until it tapered off. Which seems to be how it should be reacting. So maybe that was just an isolated incident last night?

    Sorry for all the (probably pretty basic) questions, I'm new to this and just don't want to damage anything.

  10. #9
    Registered User Monk_Knight's Avatar
    Join Date
    Aug 2010
    Location
    Colorado
    Posts
    550
    Ok, so driving home again tonight. Giving it gas in 4th and according to the AP, I hit 17.8psi. It definitely peaks in the midrange and tapers off by redline. Only really seems to be excessively boosting at night. Could it be the cooler temperatures? I've also heard that most cars will overboost some in 4th and 5th gear.

    At what point do I need to be worried? 17.8 seems pretty high, almost 3 full psi higher than target.

  11. #10
    Wants to Sell His Honyota Civilander..Any Takers? BigDaddyRex's Avatar
    Join Date
    Jan 2011
    Location
    Central NJ
    Posts
    778
    From what I understand the boost gauge feature is solid but nowhere near as accurate as a real boost gauge, so the numbers may not be 100% accurate.
    - Chris
    2011 WRX DGM (The Fastest Color) 5DR
    Cobb AP Stage 2 93, Cobb DP, RAs, STS (the dream comes true ...)

  12. #11
    Registered User Monk_Knight's Avatar
    Join Date
    Aug 2010
    Location
    Colorado
    Posts
    550
    Yeah, I was wondering about that.

    Also, I took it to the shop today to get a downpipe installed, and the shop owner said that when he took off the heatshield, he saw that the hose from the wastegate to the boost solenoid was broken. He seconded the opinion that the AP isn't the most accurate boost gauge (he said it is a *calculated* boost gauge rather than actually measuring the physical amount of boost. He also said that the broken hose could definitely be causing the issue.

  13. #12
    Registered User poly_poly-man's Avatar
    Join Date
    Feb 2010
    Location
    Rochester Institvte of Technorcery
    Posts
    1,223
    hose is cheap.

    The AP uses the ECU and a little calculation (only in that it takes output from the MAP sensor and subtracts the current atmospheric pressure - not much of a calculation), it should be somewhat accurate, or at least as accurate a reading as your ECU is seeing.
    My big thread: The Used WRX Buying Checklist - Please Contribute!

    My current car: 2002 WRB WRX Wagon.
    Mods: GM BCS, Carberry SD rom, uppipe, AEM UEGO, Klunk Killer, F+R shifter bushings, head unit

  14. #13
    Moderator Donkey's Avatar
    Join Date
    Apr 2005
    Location
    Da boonies
    Posts
    6,036
    I Support ClubWRX
    Quote Originally Posted by Monk_Knight View Post
    He seconded the opinion that the AP isn't the most accurate boost gauge (he said it is a *calculated* boost gauge rather than actually measuring the physical amount of boost.
    That doesn't make any sense. All gauges electronic or mechanical have to be calibrated and that calibration is used to correctly display data. Regardless of what gauge you use if the calibration is off,so is the data displayed on the gauge. The AP is using the ECU's MAP sensor to read the boost. Guess what an electronic boost gauge uses? A MAP sensor to read the boost. Only mechanical gauges use physical energy to display data and there isn't a single one in any car today and not to mention the past 20 years. Oil pressure sensder,water temp sender,MAF sensor,IAT sensor,cam sensor,crank sensor,knock sensor....all electrically interpret physical signals.
    Last edited by Donkey; 08-02-2011 at 08:56 AM.
    Resident Adviser @ WTF Tuning, LLC
    2002 FORESTER S
    1998 FORESTER S




Posting Permissions

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