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Old 03-31-2008, 12:55 PM   #101
The G.O.A.T.
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after reading all this i will do some testing on my 07 2.5i as well
i got the cosmo racing cai and have the same bog at idle to 1500 rpm, so if i put the snork back in with the stock air box that should work?
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Old 03-31-2008, 01:00 PM   #102
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Yup, that's the theory.

BTW, are you tuned? If you're not tuned (aka, stock ROM with CAI) I have something I'd like you to do before you put the airbox and snorkus back. PM me if you're still running the stock tune but can log with RomRaider.
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Old 04-01-2008, 03:12 PM   #103
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So I just cut the center weld on the intake (elbow grease)

It's a little crooked, but that's fine. However, my main question is this. The 2nd vacuum line plug from the TB end is really close to the center weld. I kinda started cutting without thinking about it, and now I can't put on a coupler.

Since there are only 2 vacuum lines coming out of the 05, I was wondering if I could just hack it off and put the coupler on...

Lesson: Measure twice, cut once.
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Old 04-01-2008, 05:55 PM   #104
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You only actually need 1 vacuum port prior to the TB. You can just Tee the two valvecover breather lines together and then run them into a singe port.
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Old 04-01-2008, 07:05 PM   #105
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Is it ok if the T has the same diameter in and out? Does it matter much for flow, and to relieve crankcase pressure?
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Old 04-01-2008, 09:09 PM   #106
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Dunno, I just went with a 1/2" tee. I doubt they move very much air.
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Old 04-01-2008, 10:04 PM   #107
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ah nevermind, I have two plugs on the intake. I have a tee just in case though.

I'll try fitting this thing in tomorrow.

The supports that came with this piece of junk don't fit anywhere on the intake..
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Old 04-04-2008, 11:32 PM   #108
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OK, today someone was nice enough to bring a 2.5i that was totally stock other than having an intake to my house for testing. This was the first time I had been able to log a car with the stock ROM (tune) and only and intake.

The results were exactly what I expected, but with a few twists. First, exactly as I had expected, the MAFv blows up in the low range just like on the data I've posted in the OP. Since the car is still waiting on the Closed Loop to Open Loop Transition Delay to expire, the car is still targeting 14.7AFT and using the front O2 sensor to determine the amount of AF Learning and AF Correction required to maintain a 14.7AFR. The moment the MAFv blows up, the AF Correction pegs itself negative. AF Correction alone is almost, but not quite, enough to control the situation, so the car only drops to 12.5AFR when it's trying to hit 14.7AFR. Obviously, this isn't a bad place to be, AFR wise, for power and responsiveness, but the the first interesting twist happens. With AF Correction pegged negative, the car begins populating AF Learning with negative values rapidly. Together, AF Correction plus AF Learning manage to get the rich spike under control. However, about the time that happens, the engine has accelerated out the top of the range in which the MAFv blows up. The car is still in Closed Loop waiting for the delay to expire, but now there's no MAFv to Massflow error and yet AF Learning is still pulling massive amounts of fuel out. So in the range just above where the car spikes rich, then car then spikes lean to about 15.5AFR.

Let me repeat that, because the car is waiting for the Closed Loop to Open Loop Transition Delay to expire throughout this whole fiasco with the feedback-loop variables still active, the car first spikes rich to about 12.5:1 and then almost instantly spikes lean to about 15.5:1. Looking at where people complain about "bogging" with an intake and the stock tune, I believe it's the lean spike that is what people actually feel.

Contrast this to a tune with the removal of the CL to OL Delay. A tuned car will go directly into OL as soon as the throttle is mashed. The ECU therefore won't be trying to use feedback to maintain control of the fueling. The engine will feel the full wrath of the massive rich spike, stumble, belch smoke, and buck but as soon as the engine accelerates out of the trouble range, the AFR will be proper.

The second twist is something I knew about with custom tunes but never even thought to consider in the light of the stock tune. Switching from a stock intake tract to a SRI/CAI reduces the volume between the MAF sensor and the cylinders. This leads to the stock tip-in being WAY too large. On any positive throttle movement, the car will rich spike badly for a few hundred milliseconds. This mostly just makes the car not quite feel as responsive as it should. However, if you push on the gas much at all near idle, you'll combine the over-active tip-in with the intake resonance problem and get REALLY rich for a moment WAY faster than the ECU can react to.
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Old 04-05-2008, 01:39 AM   #109
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so how do you tune that out after market fuel controller and wide band o2 sensor??
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Old 04-05-2008, 01:42 AM   #110
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I don't know that you could do it with a piggyback at all.

You MIGHT be able to if you could restrict it to engine speed below 1800RPM and engine loads above about 1.05g/rev.
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Old 04-05-2008, 02:36 AM   #111
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Excellent findings. That would explain why my car used to bog over 2k.

I did make the intake. It's a bit tight, but a hump hose on the center weld and a flexible straight coupler did the job. I had to cut up the reducer to make it fit, but I did order a proper reducer, and I'll change it when it comes.

I no longer feel the torque really kick in at 3-4K RPMs. This makes me "think" I lost power. But in reality, the kick was there from the start and it's a constant pull all the way to the redline.

Anyway, I don't feel a huge difference, but I'm always like that. Either way, the car feels peppier, but smoother. Which translates to me in my head as lost power.
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Old 04-05-2008, 02:48 AM   #112
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You really want to screw with your butt dyno, try remapping the throttle tables. You logically know the car is just as fast as it always has been because you didn't change anything other than the relationship between accel pedal angle and throttle plate angle, but butt is telling you the car HAS TO BE SO MUCH SLOWER! Makes the car easier to drive and it lurches less, but it sure as hell feels slower. After you get used to it, getting into an RS with stock throttle mapping makes you wonder why the hell you put up with such crappy light-switch throttle mapping for so long.
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Old 04-05-2008, 02:59 AM   #113
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Oh snap, you probably got rid of that ridiculous delay time, which makes everything feel like it's popping.

How long did it take to remap?
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Old 04-05-2008, 03:02 AM   #114
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Once you know what you _want_ to do, the tables are so simple it only takes about 5 minutes to type it in and reflash the car. Figuring out how it was broken in the first place was the problem because the assumption the Subaru Engineers made, that pedal angle and throttle plate angle should be equal, is an enticingly symmetric one. It just happens to be horribly wrong.
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Old 04-05-2008, 10:48 AM   #115
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Can someone clarify?

This hybrid setup will add about the same horsepower (2% less??) as a SRI/CAI?

Do I need to tune afterwards? I've never tuned before.

What did you use to cut the intake tube? Any suggestions?

Thanks!
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Old 04-05-2008, 10:53 AM   #116
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Oh...one more thing:

What model year intake do I need to order to do this? Why can't it be a SRI intake for an 06-07?

Thanks again.
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Old 04-05-2008, 01:17 PM   #117
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Does this apply to 4eat's also? cause i swear were my buddies lost low end with an intake i actually gained power from idle (i have a 05 with a cosmo sri)
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Old 04-05-2008, 02:04 PM   #118
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Quote:
Originally Posted by SleeperWgn View Post
This hybrid setup will add about the same horsepower (2% less??) as a SRI/CAI?
yes

Quote:
Do I need to tune afterwards? I've never tuned before.
Don't have to, but it'll help

Quote:
What did you use to cut the intake tube?
Hacksaw
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Old 04-05-2008, 09:50 PM   #119
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I took my 2.5i up to williaty's like he said up above. I don't really drive down that low very much so I never realized it was so bad. It sounds like the "bogging" is worse with a custom tune than with a stock one like mine, but in either case it's an accident ready to happen if you get into the right(wrong) situation. I am putting the snorkus back on as soon as I get the chance, and I'll probably do the custom intake a little later when I get some time.
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Old 04-06-2008, 04:31 AM   #120
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Quote:
Originally Posted by SleeperWgn View Post
Oh...one more thing:

What model year intake do I need to order to do this? Why can't it be a SRI intake for an 06-07?

Thanks again.
Read the first page, I wrote a step by step with a picture of the intake you need in general. (Shape is enough, you can cut it up to make it fit)

And it CAN be an intake for an 06-07, but why do that when you can get one for 40 bucks. COSMOs are getting to be more pricey.
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Old 04-06-2008, 10:28 PM   #121
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would it help to move the maf farther back??? closer to the intake farther from the filter?
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Old 04-06-2008, 10:32 PM   #122
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Possibly, but I STRONGLY doubt it.
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Old 04-07-2008, 05:55 PM   #123
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Here's a quick pic of my engine bay with my phone



It's works great and everything. My problem is that I haven't used anything to support it. It's a tight fit so it doesn't move around much, but it still wiggles a bit if I press on it, and the whole assembly moves and the air filterbox jiggles with it, which is what worries me most. Should the filter come loose, I will be ingesting craploads of dirt.

What should I use as a support bracket? And where? There are no mounting points on that ebay pipe.
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Old 04-09-2008, 03:01 PM   #124
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I just saw this post and really nice post williaty

I'm running the Cosmo SRI on my 2007 Impreza 2.5i Wagon since a full year now and I'll like to comment over this new "discover".
http://forums.nasioc.com/forums/show....php?t=1266671

First off, I see your "benchmarks" has been done with a 2005... yes the 2005 use a MAF but I think only a MAF.

But I think 2006-2007 use BOTH a MAF and a MAP sensors... well mine looks like it does with the presence of an extra sensor on the OEM torque box. Is this would change your results and opinion?

Also, I think 06-07 use more precise KWP2000/ISO14230-4 ECU vs the legacy OBD-II ISO-9141-2 used in 2005 and lower (now 2008+ use CAN of course). At least, I'm sure my 2007 Wagon connect to my ODB-II interface only in KWP2000.

And over all that, 06-07 EJ25 engine got a new intake valve lift and it as been proven here i-AVLS gives a nice kick with a SRI/CAI to 06-07:
http://forums.nasioc.com/forums/show....php?t=1156560

Oh and a side question, when you are refering to the Front O2, which one is used? Is it an average of both front sensors?


Overall, after a full year of driving with my SRI, I did'nt noticed anything wrong... neigher CEL light or "hic-up" and I run 87 octane only (89 sometimes in hot summer days).

I may agree with the fuel melange to be richer sometimes at cold start @ ~1500RPM (by the exhaust smell), specially over last winter but this is "normal" I think baceause engine start always occur in Open Loop mode and with cold temperature, catalyst never works to their full efficicency unless they've reach their running temp anyway.


And BTW, I installed a CAI/SRI on my 2 previous cars and drove them for years without any problems at all (no CEL, no hesitation, etc) It was a 2003 Sentra SE-R Spec V and 2003 Mazda Protegé5 and they were using both a MAF (and a much more cheapy NGK) and of course all the resonators were removed too.

I think ones of the main issues with MAF are vibrations. Be sure the MAF is firmly attached to the car body and the reading should be fine.

Oh and last thing, you seem to say the problem itself is a flaw in the MAF but Subaru designed a resonator to work around this flaw right? Well, what is your MAF? Mine (the stock one) is a Denso 197400-2090 (Subaru P/N 22680-AA310) the same one as the STI I think... maybe the flaw is fixed on thoses?



Thanks
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Old 04-09-2008, 03:14 PM   #125
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Quote:
Originally Posted by angel2167882 View Post
But I think 2006-2007 use BOTH a MAF and a MAP sensors... well mine looks like it does with the presence of an extra sensor on the OEM torque box. Is this would change your results and opinion?
No. I've now been able to test an 06 and an 07. Whatever the MAP sensor is used for, it doesn't have enough authority to override a confused MAF

Quote:
Oh and a side question, when you are refering to the Front O2, which one is used? Is it an average of both front sensors?
If I'm referring to the front O2 sensor, I mean the factory front O2 sensor. Any time I'm giving a specific AFR other than 14.7, it's from an Innovate Motorsports LC-1.


Quote:
Overall, after a full year of driving with my SRI, I did'nt noticed anything wrong... neigher CEL light or "hic-up" and I run 87 octane only (89 sometimes in hot summer days).
If you still have the stock tune, the car is in Closed Loop and targeting stoich in this range. This will cause it to hit 12.5:1 in the problem area (which isn't bad) but then lean out to 16:1 immediately above (which is bad). This is why it doesn't feel absolutely horrible. You can't feel how upset your car is.

Quote:
Oh and last thing, you seem to say the problem itself is a flaw in the MAF but Subaru designed a resonator to work around this flaw right?
No, you've entirely failed to understand the problem.

Quote:
the same one as the STI I think... maybe the flaw is fixed on thoses
There is no flaw with any of the MAFs
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