CovertRussian's 2012 Outback 2.5i 6MT Build

[covertrussian]

Any updates on tuning and findings?

 

I don't quite understand most of this yet. Things such as IAM, many keep saying a low number could correlate to an issue.

 

I did a ECU reset (pulled the battery and brought it in the house to float charge) a week/400 miles ago, and my IAM from two days ago is pegged at the lowest(?) possible while cruising: 0.0625. On 91ACN fuel.

 

I kind of stopped bothering trying to squeeze more power out of her, the current tune makes the best power on 87 and 93 (this surprised me). But I haven't really tried it recently because I've been busy tuning my two other cars. I have been trying to tune it for gas mileage on 87, but I haven't quite found the magic combo.

 

Your IAM is about half down. Lowest it will go is 0.00, highest it will go is 1.0. So on 91 gas is making the ECU retard half of the dynamic advance. Not surprised since I've seen IAM retard even on 93 gas in Florida heat.

 

 

Ours is a PZEV running same exact stock rom version as yours.

 

Oh that's something I didn't consider! Since yours is PZEV your tune would be slightly different. I'm not sure about the mechanical differences between regular and PZEV, but I do remember reading about PZEV's running richer on cold starts to make the cats happy (resulting in worse fuel economy)

Edited August 29, 2017 by covertrussian

[ToRealEyes]

Yup, to make both the cats on the car and the cats in CA's ARB happy. Mostly the latter. Creates more pollution, but of the less harmful type as quickly as possible. I kind of dislike the rich fuel smell on cold mornings.

 

I'm getting help with tuning the 2.5i. Let's see what happens....

[covertrussian]

So your PZEV only has two cats too? One in header and one in post header pipe before the midpipe?

 

If so then PZEV is all in the tune and by reflashing a non PZEV tune you can make it be a regular car

[GTEASER]

http://blog.subarupacific.com/explaining-the-meaning-of-pzev-with-the-2012-subaru-impreza-premium-pzev/

[ToRealEyes]

Good read.

 

So the gist of it is, our PZEV has more expensive versions of the same-ish hardware (cats, injectors, intake).

 

When it comes to tuning, ECM will 'rush' to heat up the cat to optimal operating temperature. After that point, my guess is it's no different. So far, it still drives the exact same on what I am guessing is the non PZEV (EE5K801W) map vs the PZEV (EE5K801U).

 

Maybe I should still try to get definitions made for my PZEV map. I'd be interested in seeing where [else] the differences lie.

[covertrussian]

Nice find GTEASER! I'm curious to see what the charcoal canister on the intake looks like.

 

ToRealEyes, is your car a manual or CVT? For some reason I didn't think any MT's qualified as PZEV in subaru arsenal.

[GTEASER]

PZEV was on 2.5i only with CVT in only certain States where required. Per http://www.cars101.com

[ToRealEyes]

I love cars101.com!

 

Ours is a 2012, manual, and PZEV.

[GTEASER]

I looked up the 2010. Good to know you have a 6MT.

[covertrussian]

Big fan of cars101.com too. It's what made me buy a 2012 vs 2010-11, mainly due them pointing out USB support and crossbars that fold away .

[ToRealEyes]

I found ours on a whim, got mad at local Mazda dealer for trying to pull a quick one on me for a brand new 2013 CX-5 6MT.

 

It has always driven horribly, but I knew it just needs some work. Being a Subaru, and me being a Subaru owner. One year was rear sway bar, another year was suspension, alignment, and tires. This year marks our beginning into tuning, and your threads are a huge help!

[covertrussian]

Man sorry to hear about your issues. Besides the octane fiasco and the typical lower control arm bushing issue, mine has been pretty good. But I've only put about 10k miles on it since I bought it almost 2 years ago.

[ToRealEyes]

I had to leave out a bunch of pictures because of the 20 image limit. Usually I'll split them into two posts, but Didn't want to do one post with 20 images one with ~5.

 

 

Anyway, did a virtual dyno after driving around for a day and all is well. Look at that NA power , still the car is pretty peppy for what it is!

http://i160.photobucket.com/albums/t188/covertrussian/Cars/12%20OBP/Engine/Timing%20Belt/Dyno%20-%20Post%20Timing%20Belt%20Install.png~original

 

This is SAE adjusted for Temp and Barometric pressure, but not for humidity (Virtual dyno doesn't support it, I've asked the developer to add it as a feature, but he's been MIA lately ). AFR's are actually not too bad for an NA car (assuming we can fully trust stock WBO2).

 

It's all right, I mean, they're not really issues, just Subaru nuances that I think are worth improving (and relatively easy to do so).

 

Hate to clutter your thread, but I remember seeing your post with the virtual dyno.

 

Thought I'd take a look at how our's compared, being the same and all. So! Here's a virtual dyno of our car.

 

100% stock, 91ACN gas. 4th gear to ~5200 rpm on a very slight incline. Also adjusted for that day's barometric pressure and 105* temps.

 

"Look at that NA power!" -CovertRussian

[covertrussian]

No worries on clutter, it's on topic for NA 2.5i's so I don't mind .

 

You did a 4th gear run in an outback? Man that's ballsy, that's getting up there in speed, very slowly too . A slight incline will quickly pull power too though.

 

I would do a 2nd gear pull (you'll have to add the 2nd gear ratio to Virtual Dyno). This keeps road irregularities down, and will keep you from getting in trouble from speeding.

 

Also notice that your vacuum is hitting -4inHg. I'm hitting -1inHg max throughout the powerband. That means your intake is being very restrictive, what air filter are you running and when was the last time did you change it?

Edited August 31, 2017 by covertrussian

[ToRealEyes]

Good points! Yep, I created a 'custom' vehicle in Virtual Dyno, and added in all the data. Only values I wasn't sure of was frontal area, which I used 24.01 ft^2, and C_d, which I used 0.34. I agree, this car and power level doesn't need a 4th gear log. 3rd or even 2nd would provide enough data points.

 

I'm worried about the car, since there are many instances where we are pushing it at 100%. I'm also hoping to find symptoms early through this datalogging, etc.

 

Re: the vacuum, I noticed that as well. I've got an OEM Subaru (Denso?) paper panel filter in there. Put in at 32k miles, less than 10k miles ago, and I just cleaned* it a week ago.

 

*Clean meaning thwacking it against my palm to dislodge stuff.

Edited August 31, 2017 by ToRealEyes

[covertrussian]

I create custom cars too, since my cars are always different enough from the built in ones.

 

Here are my properties...

2012 2.5i Premium

Weight: 3402lbs (verified by a scrap metal scale)

Drag Coefficient: 0.37 (found in Canadian Subaru material)

Frontal Area: 27.5^2 (I believe I calculated this one based on front width and height specs)

 

Rest will depend on your tires and transmission gear ratios (which I got form FSM).

 

Plop those numbers in and your power will change, probably increase actually since it would explain the slower acceleration to VD.

 

What filter part number did you use? There is two versions that will fit our boxes (one built for pre 2006 LGT's is less efficient then 2007+ which is what is used for 2.5i's too). If your intake track looks clean I would start blaming the exhaust track (cough clogged cats cough).

 

You can built an exhaust backpressure kit fairly easily, I'm actually gonna test my Outback pre first cat soon.

[ToRealEyes]

Thanks for posting up the properties! I'll edit my custom car profile with these when I get a chance to do another clean virtual dyno pull.

 

16546AA12A Element Air Cleaner

 

I think that's the newer one you were alluding to.

 

Lots of things for me to check. I also ordered a WIX Filter 49012.

 

Love your projects! I thought I read somewhere that the N/A Subaru engine likes a little bit of exhaust back pressure, and to avoid doing large piped exhaust mods for example. Turbo's being the opposite. Is that right?

[covertrussian]

Nice that is the new part number of the filter.

 

Love your projects! I thought I read somewhere that the N/A Subaru engine likes a little bit of exhaust back pressure, and to avoid doing large piped exhaust mods for example. Turbo's being the opposite. Is that right?

 

Thanks! I appreciate the feedback and glad it's useful to folks .

 

About NA engines liking backpressure, that's actually a myth. NA motors need velocity to help with scavenging. Scavenging is where the exhaust pulse has a negative pressure zone as it leaves the head, this helps evacuate more exhaust from the cylinder and suck in the fresh new mixture.

 

When you oversize the exhaust pipe, you reduce velocity, which reduces the scavenging and bigger diameter pipe causes the gasses to expand and cool faster, which actually results in more backpressure. So as you can see, if NA engines actually liked backpressure, a bigger diameter pipe would actually create that backpressure.

 

Now as for turbos, since everything before the turbo is under pressure usually 2:1 to 3:1 ratio of backpressure to boost, scavenging is not possible until you go with a huge 1:1 turbo. But even then scavenging is not as important because air is being forced into cylinders.

 

Instead turbos rely on pressure differentials, the greater the pressure differential between the inlet and the turbine the better. Thus turbos like huge exhausts, the bigger the better .

[ToRealEyes]

Ah yes that clears it up a bunch. So, a small exhaust leak anywhere after the headers is likely to mess with and decrease that negative pressure, thereby creating backpressure like a big exhaust would.

 

When I get a chance to take a closer look at the car this weekend, three things:

 

1. Air filter and intake path for obstructions

2. Exhaust leaks at each mating joint/gasket.

3. Blocked up cat (look for physical damage like a crushed cat, I guess)

 

We're looking at some 110*F degree weather next few days. Not sure if I'd rather have our heat or the cold winters outside California.

[covertrussian]

Right that's a good point on exhaust leaks in the manifold. Exhaust leaks further downstream are also bad, while they push out on one pulse, after that pulse they suck in air from outside, which is gonna be cold and dense = more backpressure.

 

I'm looking forward to seeing what could be wrong with your car. This kind of tells me to never buy a car without taking my tuning cable and doing some logs on the car first .

 

A friend of mine works at Subaru and he says these cats get clogged all the time. I bought a clogged cat header to see how bad it was, you wouldn't be able to see it without cutting the cat out. The one they diagnosed as clogged didn't look all that clogged after I cut it off.

 

Only other way to really know is via backpressure test, but mine is 100k in and unknown clog state

[ToRealEyes]

Right! Well, maybe it'll all be just a fluke, and a simple leak or clogged air filter. Then again, basing all this on one single log probably isn't the most error-free approach. Our car is super well maintained, and we bought it new back in 2012. Just has 41k on the clock at the moment!

 

But yea, I'm not sure how to simply diagnose a clogged cat without an actual CEL for 'cat below efficiency threshold' or something to that effect. I can imagine dealer service just saying it's within spec. I think it can be assumed that our PZEV cats are higher density than standard, so I can already expect a little less power.

 

Maybe I can pull some logs reading specific parameters for the sensors on the cat.

 

If I'm also logging very occasional misfires (haven't checked in a long time), maybe I'll consider adding a fourth item to my list:

 

4. Pull and replace spark plugs (Part Number: 22401AA731 ; 22401AA730; NGK #SIFR6A11)

 

This is fun! Appreciate all your helpful thoughts.

[covertrussian]

I would definitely look into what's causing those misfires. Misfires causes unburnt fuel to enter your exhaust stream, where it will clog up the cat (similar to a failing MAF sensor). I'm not sure how clogged a cat has to get before you throw that error, I would assume pretty darn clogged since secondary O2 sensor doesn't check for flow but for weather or not 14.7 is hit.

 

Speaking of all of this and maintenance, my fuel filter is due to for replacement at 100k miles. I pulled out the assembly today and it was dirty. I was hoping to bypass it and run in engine bay filter, but since it's a returnless system it's more complicated then that. Which means I will be bending over and overpaying for a subaru filter .

[ToRealEyes]

Re the misfires: I only logged a few misfires (total less than 3 over a few hours of driving) last winter on 87 gas, while driving in rain using my cheapo bluetooth ELM327 OBDII scanner. I chalked it up to just weird weather and bad gas. I haven't seen any misfires pop up yet during this new venture into tuning.

 

For the fuel filter, are you referring to the sock like screen that sits in the fuel tank on the fuel pump? I didn't see that as a line item on the maintenance schedule..

 

I think I can rule out intake as the culprit for now. Intake tract looked fine, and filter looked fine too. I replaced it with the Wix anyway. Couldn't get under the car to get a good look at the exhaust side of things.

 

What else have you done to optimize the intake/exhaust? What else are you seeing that might be warning flags? I'm all ears...

 

Here is a new chart with corrected car properties and a more descriptive legend. That negative boost (vacuum?), goes down to -6 psi and maxes out at -12.33 psi (-11 inHg to -23 inHg). I believe the plot is read off of the Manifold Relative Pressure (psi) parameter. Am I looking at the right place for clues?

[covertrussian]

Fuel filter is integrated into the fuel pump assembly now (more so then Legacy GT's have it), the sock is still there too, but not as big of a deal. The fuel filter part number is 42072AJ060, look up pictures of it, you'll see what I mean. There are two cylindrical shapes on it, one is for fuel pump to go into, the other is the actual fuel filter. The pre-filter that your talking about is actually called a fuel pump strainer.

 

Subaru used to say you never have to replace the in-tank fuel pump filters, they would say "life of the car". But with 2010+ looks like it's now on a 60k mile service interval.

 

I took mine out last weekend to see if I can bypass it and to in engine bay one (like I did on my GT), no dice because it's a returnless system and the fuel pressure regulator is part of the assembly. Damn you Subaru!!!! Thus I ended up ordering a new OEM one sigh.

 

 

Anyway back to air filters, is WIX as highly regarded filter? I'm not familiar with them, but I would almost say get an OEM one, or another one that's not WIX, just to rule out the filter.

 

Your air to fuel ratios are pegging the stock wideband at it's lowest reading (11.1:1 afr). If you look at my graphs, you'll see my AFR's go to 12's at worst (this is on stock fueling). This along with high manifold vacuum at WOT further tells me that your having an air delivery issue.

Edited September 6, 2017 by covertrussian

[ToRealEyes]

Ah right, the whole thing huh. I looked at the service manual, and it's funny that they say "Replace if the filter is clogged, or time for replacement has come." If I were to open it up to inspect, I think I'd just replace as well, after going through all the trouble already. I'm not seeing an interval on the schedule though...

 

Wix is pretty middle of the road, and adequate considering my short intervals (10-15k) anyway. Cost is less than 1/2 a new OEM Denso filter, so I went with the Wix filter to do some experimentation.

 

When I cracked open the airbox over the weekend, there was an additional filter screen/mesh panel between items (7) and (8), ie. after the panel filter.

 

I looked closer at the diagrams for the intake airbox for our year (2012), and what I saw doesn't appear on exploded view. I didn't try removing the mesh panel. from the rear of the airbox. Should I?