Ixiz AOSep install tips

[NSFW]

This isn't much of a walkthrough since I didn't think to take pictures until I was well into the job, but on the other hand, it's not that hard... and if you learn from my mistakes, it will be even less hard.

 

Stuff you will need that's not in the box:

 

* Three 1/2" to 5/8" hose joiners - the Ixiz kit comes with 1/2 vent hose and a 3/8 drain hose, and maybe that works on an STI, but the LGT head breather hoses are bigger. The Ixiz-supplied fittings just fall into the hoses. 5/8" fittings (aka 16mm) will do the trick.

 

* A place to mount the thing. The place suggested in the instructions, next to the passenger side strut tower, might work great in Imprezas, but it's full of brake stuff in the Legacy engine bay. I bought a strut bar for $40ish off eBay, which provides a nice flat mounting surface. There are cheaper ways, but I'm happy. Plus I got a strut bar out of the deal, even if it does have a couple holes in it now.

 

Be advised the the middle of the strut bar has a vertical reinfocement rib - a drill will want to go around it, not through it. Don't fight it.

 

Also note that the mounting bracket will accommodate the angle of the strut bar if you choose to mount it off to the side. It's a pretty neat mounting system.

 

* Hose clamps. You'll notice I don't have any on the ends of the head breathers. I used all the ones supplied with the AOSep and it didn't come with clamps suitable for 5/8" anyway. I think I need three more for 1/2" hose and two more for 5/8"... but I should have taken notes while I had the car in front of me.

 

* Optional: if you have a data logger, start the engine and look at "AF #1 Learning A." It's probably a number between -5 and +5. The actual value isn't important, just remember it for later.

 

If you bought the mounting bracket, be advised that the slots in the top of the bracket are different sizes. I guess Ixiz has a sense of humor.

 

http://i193.photobucket.com/albums/z151/Legacy_NSFW/AirOilSeparator/AOSep1.jpg

 

If you have a TMIC, you might not be able to fit the AOSep in the place where I put it. Investigate before you start drilling. Also, you will need to remove the TMIC to get access to the hoses behind/under the intake manifold. I have a FMIC, so I got to skip that step. Neener neener.

 

After deciding where the AOSep should be mounted, I put it back in the garage and plumbed everything that doesn't connect to the AOSep unit itself. It's crowded under the manifold, I wanted space for my elbows.

 

You'll need to remove the hard plastic tube that connects the head breathers. The head breather tube is mounted below and behind the manifold. The picture below was taken much further into my install, when it occurred to me that I should be taking pictures. Note the 1/2" to 5/8" joiners already installed in the head breather tube at the bottom of the picture.

 

 

http://i193.photobucket.com/albums/z151/Legacy_NSFW/AirOilSeparator/AOSep6.jpg

 

Each end is easy to disconnect, the middle connection to the inlet tube is not too hard, but wiggling the thing out from under the back of the intake manifold was a bit of a struggle.

 

Once removed, it will leave behind a 1/2" hose to the turbo inlet, sitting just under the manifold, which is visible in the image below (again with a 1/2" to 5/8" joiner already inserted).

 

The instructions are a bit vague about the first hose to remove. I made the mistake of not photographing it after I removed it... but below you can see where it was originally located:

 

http://i193.photobucket.com/albums/z151/Legacy_NSFW/AirOilSeparator/AOSep5.jpg

 

That pic was taken looking downward over the turbo. If you have a TMIC, the blue area at the bottom will be looking into the compressor outlet.

 

In the picture, note that the supplied cap has already been intalled over the barb on the turbo inlet, at the bottom right.

 

The instructions suggest putting 3-4 inches of supplied 1/2" tubing on the PCV valve (the barb on the left, in the picture above), but I found it easier to put the factory hose back in, just rotated 90 degrees. Then I stuck the AOSep drain tee into it - that's the 1/2" x 3/8" x 1/2" tee.

 

Install AOSep.

 

Run the 3/8" drain hose from the valve on the bottom of the AOSep to the drain tee.

 

http://i193.photobucket.com/albums/z151/Legacy_NSFW/AirOilSeparator/AOSep2.jpg

 

Plug the 1/2"-to-5/8" joiners into the ends of the factory head breathers, and run a section of 1/2" tubing between them. Mark the middle, cut, and put in the Ixiz-supplied 1/2" tee fitting. Run a 1/2" ventilation hose from that tee to an inlet on the side of the AOSep. This carries oil and mist and crap out of the engine.

 

http://i193.photobucket.com/albums/z151/Legacy_NSFW/AirOilSeparator/AOSep3.jpg

 

Run a 1/2" ventilation hose from the drain/crankcase tee to an inlet on the side of the AOSep. This carries oil and mist and crap out of the engine.

 

Run another 1/2" ventilation hose, this time from the outlet hose on the AOSep to the turbo inlet hose under the manifold. This carries pure unadulterated air back to the inlet. That's the whole purpose of the air-oil separator.

 

http://i193.photobucket.com/albums/z151/Legacy_NSFW/AirOilSeparator/AOSep4.jpg

 

Put hose clamps everywhere.

Or don't. As you can see, I didn't.

But I will tomorrow.

 

Then start the engine. If it idles like you'd expect, you probably did it right.

 

Since you're messing with hoses that are under vacuum, any mistakes will probably manifest themselves as vacuum leaks, which will make the engine idle poorly. If you have a data logger, watch "AF Learning #1 A." It should stay steady at the same value as before, plus or minus a tenth or so. If you have a vacuum leak, it will steadily climb to +15 (maybe +20 or +25 depending on your tune).

[NSFW]

Part II: Advanced Considerations

 

There's a pretty interesting thread over at IWSTI about different ways to plumb an air-oil separator. There are basically two approaches under consideration, the "Ixiz way" and the "Crawford way."

 

The Ixiz way is very similar to the stock setup. It just adds a separator and a drain return line. The stock setup uses the head breathers to supply fresh air to the heads when the intake manifold is in vacuum, but when in boost, the head breathers flow the other direction.

 

The Crawford way removes the PCV valve. This makes the head breathers exit-only. I was actually planning to do it the Crawford way because I think it's slightly better... but I couldn't reach the base of the PCV valve. I'm going to take my manifold off to install a bigger turbo in a couple weeks, and I'll consider it then.

 

I have two concerns about the stock/Ixiz approach:

 

1) I doubt the separator works optimally when the car is out of boost. In fact I don't think it works at all. Gases get sucked from the turbo inlet, backward through the AOSep, and into the throttle body. There probably isn't much blow-by when out of boost, though.

 

2) Eventually I want to switch to blow-through MAF, which requires deleting the PCV valve and using "Crawford"-style separator plumbing. The PCV valve is basically a vacuum leak from the perspective of a blow-through MAF sensor.

 

But until I switch to blow-through, I actually don't feel too strongly about it. I'm sure the Ixiz recommended plumbing will work better than stock, I just think the PCV-valve-less approach will work quite a bit better. Read the thread and choose for yourself:

 

http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/146699-official-sti-engine-venting-o-separators-catch-cans-thread.html

[trademark]

Awesome write up! I don't think that an AOSep is in my list of to-do $300 mods though.. I'm assuming you are concerned about engine life? or you will be running such high boost that this thing will save you quarts of oil.. hehe. j/k but seriously sup with this thing?

[NSFW]

 

I'm assuming you are concerned about engine life? or you will be running such high boost that this thing will save you quarts of oil.. hehe. j/k but seriously sup with this thing?

 

Yes, both of those. I'm hoping for about double the factory horsepower, so I want to do whatever I can to keep the engine healthy. Catch cans sound like a hassle, so I like the separator idea more.

 

It occurred to me that with catch cans, I'd know how much blow-by I was getting by the rate at which the cans fill up... but by the time they start filling too fast, it's too late anyway.

[crash]

I installed mine over the weekend after consulting with Ming from Izix.

 

He actually suggested that I install it the "Crawford" way.

 

I took off the PCV (the metal barb in pic 3) (it unscrews from the factory 3 way connector) Then drilled out the one way check valve (it was difficult, even with a drill press) and attached the 3/8 drain from the AOSep.

Then I capped off the factory tube that went from this to the intake manifold.

 

I also retained the factory hard pipe for my valve cover breathers... but it was a biach getting the hoses on since it angles under the intake manifold.

[NSFW]

I installed mine over the weekend after consulting with Ming from Izix.

 

He actually suggested that I install it the "Crawford" way.

 

I took off the PCV (the metal barb in pic 3) (it unscrews from the factory 3 way connector) Then drilled out the one way check valve (it was difficult, even with a drill press) and attached the 3/8 drain from the AOSep.

Then I capped off the factory tube that went from this to the intake manifold.

 

I also retained the factory hard pipe for my valve cover breathers... but it was a biach getting the hoses on since it angles under the intake manifold.

 

Thanks for the info, that's very interesting. I'm going to have the manifold off for a turbo swap soon and I'll delete the PCV valve when that happens.

 

Is it really necessary to drill it? I mean, why not just use a plastic fitting like all the other joints?

[crash]

That Factory T fitting has a metal threaded part for the metal PCV. I probably could have taken it to Home Depot and found a barb fitting that would have screwed in, but there was no guarantee it was a standard air fitting size thread... So I just drilled it out...

 

It has to be drilled out because that valve only opens when the intake manifold is under vacuum.

[LittleBlueGT]

I am strongly thinking about getting this AOS, but I don't think I will be able to fit it with my new TMIC that works with STI style turbos.

 

Any reason why I couldn't run the AOS in the spot where the OEM airbox sits, then run the oil return line to a simple sealed empty-able container?

[crash]

I mounted mine to the strut tower..

 

I had to drill a few extra holes in the bracket, and remove the existing bracket that holds the wiring harness, but it fit nicely...

[LittleBlueGT]

I mounted mine to the strut tower..

 

I had to drill a few extra holes in the bracket, and remove the existing bracket that holds the wiring harness, but it fit nicely...

 

My new TMIC will likely block that, it will look like this:

 

http://www.legacygt.com/forums/showpost.php?p=2559112&postcount=18

[NSFW]

There's a drain line on the bottom of the unit which should be higher than the top of the crankcase. Otherwise the separated oil/water will pool in the separator until it reaches a level high enough to spill into the case.

 

I'm not sure how critical it is - there may be some allowance in the design for pooling like that. But higher just seems better.

 

Hanging it off the strut tower next to that big wiring connector seems reasonable. The higher you can get it, the better.

[LittleBlueGT]

And if it won't fit up there?

 

Why won't my idea work:

 

Any reason why I couldn't run the AOS in the spot where the OEM airbox sits, then run the oil return line to a simple sealed empty-able container?

[NSFW]

LBGT and I talked offline, and I just realized I never followed up in the thread. Yes, if you're going to drain it into a container (rather than draining back to the engine), I think it'll be fine to mount it anywhere.

[NSFW]

Also, I'm now running mine without the PCV valve. Stuff flows out of the case/heads and into the turbo inlet. I've been thinking it might be a good idea to use the PCV valve itself, but plumb it in so it pulls from the separator rather than straight from the case. But I'm in no hurry to change anything.

[2.5gtbx_44]

Can i get a visual break down of the last pic? Wit little arrows or something showing which hose does what and where it goes. I am having an issue wit a breather system that i had installed and i wanna check if mine is setup the same way and maybe could be the cause of my problems.

 

Thanx and sorry for bumping an old thread

[NSFW]

Which way things flow depends on whether the PCV valve is left in place. I'll describe the PCV-less setup since it's simpler. The separator has three fittings on the side shown in that picture:

 

1

 

2 3

#1 is the outlet, which flows 'cleaned' air to the turbo inlet.

#2 and #3 are inlets, which let 'dirty' air/oil into the separator.

 

Dirty air flows from out from the crankcase and head breathers, through the separator (coming in via 2 and 3), and then out (via 1) to the turbo inlet. This is all drive by blow-by pressure. If no blow-by, the air is still.

 

If you leave the PCV valve in place, the above is still correct when you're in boost.

 

But, when in vacuum, air gets sucked from the crankcase vent into the manifold. To supply air to the crankcase, the flow in the turbo inlet connection is reversed.

 

In the stock setup, air flows from the turbo inlet to the head breathers to the crankcase (via passages in the motor or via 'jumper' hoses between the case and the heads - I'm not sure which, and it might vary by model year). With a separator installed as shown above, the flow in the head breathers (and in the separator, near the head breather port) is hard to predict. I don't like the idea of reversing the flow through the separator though, which is why I removed the valve.

[2.5gtbx_44]

ok cool got that. Now where is the drain connected to? The reason i ask is because i had a breather system installed last week and i have a feeling it was installed incorrectly. I am now having a turbo issue which i believe is from the incorrect installation of the breather. I believe the crankcase pressure is getting blown up the oil drain tube of the turbo. The reason I say that is because the hose that appears to be the drain hose looks like its plumed into the pcv valve!?! Idk what is going on. Also i am vented to the atmosphere with two breather filters.

 

Thank you in advance for your input

 

4.2 Turbocharger "Seals" and

Crankcase Pressure

The turbocharger “seals” play a secondary role in turbocharger oil control since the oil slingers are designed to prevent oil from reaching the seal areas. The primary role of the turbocharger seals is to prevent external gases (i.e., boost pressure and/or exhaust gas) from entering the center housing. Under most operating conditions in a blow-thru configuration, the gas pressures in the compressor and turbine housings are equal to or greater than the gas pressure in the turbocharger center housing (i.e., engine breather pressure). In this configuration, the pressure on the turbocharger seals is from the outside toward the inside and is actually trying to push any oil near the seal areas into the turbo.

If the engine breather system has been modified so that the engine crankcase cannot breathe and is causing excess crankcase pressure, this pressure is transmitted to the turbocharger center housing via the oil drain tube. In this situation, the crankcase pressure in the turbo center housing may exceed the compressor and/or turbine housing pressure; therefore, the pressure on the turbocharger seals is from the inside toward the outside and the crankcase pressure will push oil out of the center housing into the compressor and turbine housings. Excess crankcase pressure may be caused by engine breather modifications such as improperly installed performance breathers/catch cans or by worn or damaged engine components (i.e., pistons, rings, or cylinder walls) that result in severe combustion gas blow-by that pressurizes the engine crankcase and turbocharger center housing.

[keysersoze]

I mounted mine to the strut tower..

 

I had to drill a few extra holes in the bracket, and remove the existing bracket that holds the wiring harness, but it fit nicely...

 

If you find the time, please post some pics of how your is mounted.

 

Thanks

[NSFW]

ok cool got that. Now where is the drain connected to? The reason i ask is because i had a breather system installed last week and i have a feeling it was installed incorrectly. I am now having a turbo issue which i believe is from the incorrect installation of the breather. I believe the crankcase pressure is getting blown up the oil drain tube of the turbo. The reason I say that is because the hose that appears to be the drain hose looks like its plumed into the pcv valve!?! Idk what is going on. Also i am vented to the atmosphere with two breather filters.

 

I have a T fitting where the PCV valve was, basically it plumbs the separator's oil drain into the vent tube that runs from the crank-case to the separator. (The drain line has a one-way valve to keep things from flowing the wrong direction.) So, yours isn't necessarily installed wrong.

 

If the crankcase is pressurized and not vented, you'd probably have the dipstick popping out, or you'd hear a hiss when you pull the dipstick out.

 

What exactly is vented to atmosphere?

[2.5gtbx_44]

the air that is separated by the breather. Where you have a hose going back to the inlet, I do not. You removed your pcv valve and replaced it with a T fitting. My pcv valve is still there and has the drain hose plumed into it. ill take a pic and post it in a few. Maybe im just looking for a reason to why my turbo is acting up and its just a coincidence that it starts right after i got the breather done. Its just kind of hard to believe that it is that big of a coincidence.

[2.5gtbx_44]

Here are the pics:

 

The first pic you can see the drain hose on the bottom of the breather unit. The hose on top is from one of the head breathers.

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC00993.jpg

 

In this pic you can see the two hoses that go to the breather from the head breathers. They put one input for each head breather.

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC00994.jpg

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC00995.jpg

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC00996.jpg

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC00997.jpg

 

This pci you can see that hose is from the drain and is plumed right into the pcv valve.

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC00998.jpg

 

The inlet hose blocked off from the inlet hose.

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC00999.jpg

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC01001.jpg

 

http://i79.photobucket.com/albums/j133/s13slider44/DSC01002.jpg

 

This is not the way it is setup but, to me it seems as if something is missing from my setup. IDK

 

http://i79.photobucket.com/albums/j133/s13slider44/CrawfordInstalled.jpg

[trademark]

I never realized that setup is right over the turbo....

[NSFW]

Seems reasonable to me. Since you're not routing the blow-by gases to the inlet, getting the oil separated from the air is less critical, which means you can use a simpler separator and simpler routing.

 

If you follow the line that comes up from the crankcase in the diagram you posted, you'll notice that it splits into two lines that just go up to the separator. I'm actually not convinced that the split is absolutely necessary, even for the Ixiz unit. And since your setup vents blow-by gases instead of routing them to the turbo inlet, that line on the far left of the diagram doesn't exist. If you make those two changes to the diagram, it matches your setup.

 

Most importantly - since you've got the separator vented, your crankcase pressure is probably normal. I don't know what's up with your turbo but I doubt the separator is the root cause.

[2.5gtbx_44]

right but, to me it seems as if the drain in my setup is draining the oil if i am not mistaken into the pcv valve like this:

 

http://i79.photobucket.com/albums/j133/s13slider44/CrawfordInstalled1.jpg

 

I do not see where the other vent is by the question mark in my set up.

[NSFW]

I never realized that setup is right over the turbo....

 

It gets enough air flow through hood scoop that it stays cold when I'm driving. I'm actually not sure if that's a good thing or a bad thing. On one hand, being cold should help the oil condense onto the sides of the separator. On the other hand, being cold probably also contributes to sludge buildup (aka mayonnaise), especially on the oil drain line. At some point I need to look inside that line and see if it's clogged...