02 Wrx boosting low?? O2 Sensor??
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This is a discussion on 02 Wrx boosting low?? O2 Sensor?? within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Flashed my car using AP to stage 1 93 today. I have a CEL for P0031 Front oxygen (A/F) sensor ...

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    02 Wrx boosting low?? O2 Sensor??

    Flashed my car using AP to stage 1 93 today. I have a CEL for P0031 Front oxygen (A/F) sensor heater circuit low input. I am only peaking at about 11psi. I feel like it should be higher. Especially with the stage 1 flash. I feel like it should be around 15-16. Would the oxygen sensor be causing the car to boost low? The car is completely stock except for a CAI that the previous owner had put on there. Putting on the stock intake by the end of next week waiting for a few more parts to come in. The car has always been boosting low, it's just now that I realized it when I plugged in the Accessport to read the boost as well as my boost guage both confirm that I am peaking around 10???? What the heck

    Any input would be appreciated! Thanks!

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    Registered User teflon_jones's Avatar
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    Was the CEL there before you flashed, or only show up after?

    The AP maps specifically say what intakes they're designed for (if any). Using anything other than what they specify can lead to problems, so that could be your issue right there. What exact intake is it?

    And yes a bad o2 sensor could certainly cause boost issues. You may have a vacuum leak too. How long has the car been doing it for? Mileage and service history please.
    Scott
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    Yes the CEL was there before I had flashed it and it was for the same exact thing, which is the oxygen sensor. The car has 80,000 miles, just put in a brand new oem exedy clutch, new tranny fluid, oil and filter change, new valve cover gaskets as well as the rear main seal. I know how CAI and wrx's are not the best for each other, that is why I purchased a stock intake and I am waiting for the Chamber ASSY as well as the snorkel to come in so I can get rid of the CAI asap and replace it with the stock intake. Today, I flashed the ecu to stage 1 like I previously said and used the AP to monitor the boost and compare it to my boost gauge. It holds steady at 0.5 mpa in first and second gear and then around 0.6-0.7 mpa in 3rd-5th. I know that it should be hitting around .1mpa stock and maybe slightly a little higher with the ecu flashed to stage 1. The car has been on low boost for a while now, its just until today that I realized that it should be hitting more boost and that I have some sort of a problem I would be alot more happier if I were hitting 15 psi opposed to 9 that I am hitting currently

    Let me know if you need anything else. I can even post a vid up by tomorrow if you want to hear what it sounds like because I do feel that there could be a boost leak somewhere.

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    Registered User teflon_jones's Avatar
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    Based on your information, I'd start with looking for a boost leak (along with putting the stock intake back on). I'd also get a new sensor to replace the current one throwing a code.
    Scott
    Past Subies - '11 STI Limited stage 1+ and '04 STi stage 2+
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    Registered User Shansen2's Avatar
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    ^^ what he said. My friend had this same problem, but instead of putting the stock intake on he got the stock sti one and it worked fine.

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by Shansen2
    ^^ what he said. My friend had this same problem, but instead of putting the stock intake on he got the stock sti one and it worked fine.
    Because it's the same part
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    I will replace the 02 sensor and put the stock intake back on and clean the MAF and search around if there is still a boost leak. I'll get back to you guys

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    Registered User Shansen2's Avatar
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    Quote Originally Posted by EJ257 View Post
    Because it's the same part
    haha ok i wasn't sure but i guess it is

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    Quote Originally Posted by Shansen2 View Post
    ^^ what he said. My friend had this same problem, but instead of putting the stock intake on he got the stock sti one and it worked fine.
    So your saying that he was boosting lower because of a cold air intake and when he replaced it with the stock intake it fixed it?

  11. #10
    Registered User Shansen2's Avatar
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    Yes, the cold air intake was messing with his car, not sure the exact reason.

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    Ok so I looked at some of the boost lines and I found something

    So what I found is a hose pretty much cut in half being held together by some like weird device. It's barely even holding it in, I can literally flick it out/pull it out without using any force. I took some pics to show you what I'm talking about. Apparently this hose goes from the intake to the boost controller solenoid?



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    Uploaded with ImageShack.us



    Uploaded with ImageShack.us

    Hope this is the problem to my boost issues! Still have to replace the o2 sensor however. Let me know what you guys think

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    Sure enough that was my problem! Peaked at about .11 mPa today and held steady at .1!

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