2004 WRX Oil in Intercooler?
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This is a discussion on 2004 WRX Oil in Intercooler? within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; Hi all, I just picked up a sweet 2004 WRX wagon: It has 195,000 on it but runs strong and ...

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    Registered User wingman358's Avatar
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    2004 WRX Oil in Intercooler?

    Hi all, I just picked up a sweet 2004 WRX wagon:

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    It has 195,000 on it but runs strong and feels solid. I could tell before I bought it that it's been taken care of pretty well. Boost peaks at ~ 13 psi if my Cobb AP is to be trusted. The interior looks almost brand new and the body is in decent shape as well.

    Only issue that I am sort of concerned about is the PO told me she burns about a half quart of oil between changes. I'm no Subie expert by any means, but just looking around the engine bay, I've noticed a decent amount of oil residue/grit build-up around the edges of the intercooler outlet hose. I have also read that Subies have a tendency put oil through the intake by way of the PCV. It's my understanding that the horizontally-opposed arrangement naturally lends itself to more oil mist being vented from the heads.

    That all being said, I wonder if my disappearing oil could potentially be leaking, for lack of a better word, into the intake through the crankcase venting.

    I think this may be the motivation behind air-oil separators and "catch-cans." I plan on testing this theory on my own WRX, with an inspection of the intake system both before and after an AOS installation. I plan on removing all of the intake piping (intercooler included) for examination and cleaning, then reinstalling with an AOS in place. I don't think I'll go 200,000 miles before the after-installation inspection, but a couple thousand miles should be enough to see a general trend.

    I had a Ford Ranger before this that had a rear-main leak, it would drip on the driveway everyday, at work, etc, and it went through about a quart every 3k miles. Not really a problem if you keep on top of it, check the level frequently. I actually saw it as a good thing, because it kept me in the engine bay and crawling underneath. And everywhere there was leaked oil, there was no rust. Win!

    What do you guys think? I've heard of brand-new WRXs with barely 500 miles on the odo having oil pooled inside the intercooler, so to me, this seems a likely occurrence. Aside from the decrease in intercooler cooling effect on the intake charge, and the small amount of burnt oil, is there any real downside to oil in the intake air?

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    Moderator Donkey's Avatar
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    Yes it is mainly due to PCV gases as they are routed in front of the turbocharger under boost. Under vacuum the gases are routed in to the intake manifold via the PCV valve. ALL cars benefit from a catch can/AOS. The down side to PCV gases/oil in the intake besides as mention above (decrease in heat transfer for the intercooler) is the effective reduction of octane/knock threshold. Not to mention dirty and gunked up piston tops/valves.

    http://forums.nasioc.com/forums/showthread.php?t=533787
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    Registered User wingman358's Avatar
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    Donkey, which of Una's FAQs were you pointing me toward?

    I've been devouring everything I can find on the ej205 and mods for it, and his posts keep coming up.

    Honestly my favorite mod thus far has been eliminating various interior rattles (A-pillar trim, steering column, trunk light cover, radio bezel).

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    Moderator Donkey's Avatar
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    I just threw it up there for you to browse. There should be a catch can/AOS FAQ's along with an oil one. I typically do not run 5w30 in any of my Subarus. I like running a 5w40 synthetic. Generally Rotella T6 or Casteroil. Less issue with consumption. Generally it takes two catch cans to do it right. For the AOS you just need one as it is designed to accommodate the factory PCV system.
    Last edited by Donkey; 11-11-2014 at 07:58 AM.
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    Registered User wingman358's Avatar
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    Thanks. Do you have any other resources you can direct me towards regarding the ej205?

    I've found WRXinfo is pretty good, and NASIOC has a lot of good info, just have to wade through all the riff raff.

    Also, regarding oil ending up in the intake system, is it possible that it could gunk up the IAC system? According to the PO, the IAC on my car had some issues recently of sticking closed and stalling when coming to a stop/idling. Said he cleaned the IAC and it fixed the issue. Seems to be a fairly common thing on these cars.

    Just wondering if the oil in the intake could be partly causing that valve to stick- what do you think?

    If that's true then the AOS would be worth it for the prevention of gunking up the IAC, not to mention the other benefits.

    In terms of oil, I've heard over and over that Rotella T6 is one of the better ones for the WRX. PO said he used it, and I plan on using it too. I've been running T6 in my Ninja since the first oil change and never had any issues.

    Only thing I am curious about is the Canadian T6.. Apparently it's made in 0w40 weight for the Canucks. Do you think it's worth trying to find?

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    zax
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    Precisely what do you want to know about the EJ205? I'm not sure there's anything out there regarding the EJ205 or 16bit ECU architecture that will stump Donkey or myself (yes that's a challenge lol).
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    Moderator Donkey's Avatar
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    Your asking a lot of questions that have obvious answers...
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    Registered User wingman358's Avatar
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    Quote Originally Posted by zax View Post
    Precisely what do you want to know about the EJ205? I'm not sure there's anything out there regarding the EJ205 or 16bit ECU architecture that will stump Donkey or myself (yes that's a challenge lol).
    Just looking for a good overall technical resource aside from the service manual. In terms of specific questions, my A/F Correction 1 is around +8%. Any idea what could be causing that?


    Quote Originally Posted by Donkey View Post
    Your asking a lot of questions that have obvious answers...
    I do have a tendency to ask dumb questions This is my first Subie so I'm just trying to reason through things and see if anybody else agrees/disagrees or has experience with what I'm thinking about.

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    Moderator Donkey's Avatar
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    Quote Originally Posted by wingman358 View Post
    In terms of specific questions, my A/F Correction 1 is around +8%. Any idea what could be causing that?
    Most cars with the stock MAF scaling will see that. Not ideal,but completely normal.
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    zax
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    Quote Originally Posted by wingman358 View Post
    Just looking for a good overall technical resource aside from the service manual. In terms of specific questions, my A/F Correction 1 is around +8%. Any idea what could be causing that?




    I do have a tendency to ask dumb questions This is my first Subie so I'm just trying to reason through things and see if anybody else agrees/disagrees or has experience with what I'm thinking about.
    There is no such thing as a dumb question. Many questions already have answers. Some of those questions have answers that are easily accessible.
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    Registered User wingman358's Avatar
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    Quote Originally Posted by Donkey View Post
    Most cars with the stock MAF scaling will see that. Not ideal,but completely normal.
    Since I am looking to get the car running as nicely as possible, I assume it would be advisable to adjust the MAF scaling. Isn't it also possible that there's a vacuum leak/unmetered air though?

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    Moderator Donkey's Avatar
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    2004 WRX Oil in Intercooler?

    With out seeing all of the fueling corrections impossible to know if it has a vacuum leak or not. Of your worried about then smoke test the system. Regardless it is still seeing 14.7:1 AFR
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    zax
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    Quote Originally Posted by wingman358 View Post
    Since I am looking to get the car running as nicely as possible, I assume it would be advisable to adjust the MAF scaling. Isn't it also possible that there's a vacuum leak/unmetered air though?
    You would need a WBO2 sensor to adjust the MAFv scaling.

    You COULD try to adjust scaling with CL data (there are detailed threads about this), but this is unwise without cross-checking the OL fueling with a WBO2. Global scaling adjustments are usually compensated by the injector scaling, but if you have a vac-leak, this is also unwise.
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