Intake Silencer Removal

[jedimaster]

This walkthrough is done on an 05 Outback XT- I'll assume the Legacy GT is mechanically the same in this aspect. 2.5i models may differ.

I was changing the oil in my car, having reached the end of the 1000 mile breakin period (By the way, changing the oil on the XT is nice- the ground clearance means you don't need ramps). I've been thinking about the intake silencer, so while I waited for the oil to drain, I started taking the silencer apart.

Before I get into the walkthrough, this is a good, easy, reversible and free modification you can do in about 20 minutes. It's also good for someone who has never done mods and would like to start with something not tooo intimidating.

Begin by removing the 2 popit screws from the ait scoop- the scoop will now slide out:

http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-001.jpg

Next, you'll see 2 bolts on the bottom of the airbox. The front one is easy, but the rear requires an extension. Use a 10mm socket for these:

http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-002.jpg
http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-004.jpg

There's a 3rd nut holding the box in- it's up front by the passenger side headlight. Use a 10 mm open end wrench to get this one off.

http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-003.jpg

Unlpug the electrical connection on top of the airbox and undo the worm gear screw holding the intake hose onto the airbox.

http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-005.jpg

I found it easiest to remove the air filter, then take the rear half of the airbox out. After that, you can wiggle the rest of the airbox and intake silencer out of the car- this is what it looks like:

http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-006.jpg

Inside, you can see the tiny hole where air is moved down and silenced:

http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-007.jpg

Subaru must have gotten smart and realized people would hack these up, because there's another of those popit screws holding the silencer onto the airbox- this one is white. There are also a pair of tabs you can depress to take the silencer off the airbox. One of these is visible in the picture- the other is on the opposite side.

http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-008.jpg

The best way to get things back together is to put the filter back in the box and put the two halves of the filter back together. Then it's a matter of putting the airbox back in and bolting everything back up in the reverse order of removal.

What you're left with is a very stock looking car- you can't see the silencer from the top of the car, as it is tucked down into the front bumper. So the bottom line is nobody would know it was missing unless they took a real close look, and removed the airscoop, etc.

http://premium.uploadit.org/cultofthejedi/intake-silencer-removal-009.jpg

I took a drive after doing this and even on startup, you hear the extra air being sucked up. Idle seems a little louder on the intake side, as expected. On boost, the engine has a lot more growl to it and you can hear the turbo spool and if you push the clutch in, you can hear it spin and slow down. I can't say for sure, but the car also felt a little faster. This may be one of those cases where the ECU will learn the change and compensate for it eventually. Only time will tell. At any rate, if you have any questions, please ask. :)

Jim

[STEye]

I can't say for sure, but the car also felt a little faster.

Jim, you're the man with the writeups! Hey if the butt dyno says its fastar, then it's fastarrr.. It no lie! :p

[ih8vtec13]

i did this last winter after my after snowboarding smoke back at the house :) A little differance in sound and i can finaly hear my turbo :)

[jedimaster]

It's particularly nice in the warm weather when cruising with the windows down. Watch people in traffic look at you wondering where that flux capacitor sound is coming from:lol:

[Drift Monkey]

[.commie]OMG this mod sux. I put mine back back on right after because of how much it sucks![/.commie]

[jedimaster]

[.commie]OMG this mod sux. I put mine back back on right after because of how much it sucks![/.commie]
Yeah, that was pretty much what I got for my trouble :lol:

[NALegacy]

Oh yeah, this works exactly the same way for the N/As...and I believe you actually do get a bit of power w/ the removal, as the N/As could use any help they can get:rolleyes:...ghetto fabulous cold/normal dual air intake FTW!

[STEye]

Who needs those stinkin' silencers anyway?? I think car companies put them on for the yuppies!

[Effin Ponderous]

Ha...did my first free mod! I can actually hear something now. It really sucked having to turn down the radio and open the window to hear if the engine was running!

[jedimaster]

Glad you liked it!

[Effin Ponderous]

Hmm...what I really meant to say was thank you sir, may I have another!

Hey and to answer anyones worries about sucking up water or anything else...

I went to leave work today in Newark. We had torrential rains for all of 5 minutes before we left. By the time I was a block away every intersection started flooding. I got caught in the middle of the road with no where to go and angry 4wd's behind me honking. It took a while but I made it through without a hitch. No sucking water from the open hole.
Sorry for the camera phone pics

[TSi+WRX]

^ Damn! That's a lot of rain! :eek:

Glad to hear that you made it through OK on your little "crossing adventure!" :)

Although I've been worried about such crossings (there's about two areas, locally, which I know can get that deep) due to the low location of our Boxer engines, there have been documented cases on LGT.com - as well as your own, now - that have truly eased my mind about the stock ride-height LGT's as well as even lowered (as yours) LGT's ability to perform such emergency maneuvers, when there are simply no other options....

Good stuff!

And keep safe, my good brother! :)

[andrew.anderson]

Effin Ponderous,

Nice rain pics! No car damage? It looks deep.

[Effin Ponderous]

Effin Ponderous,

Nice rain pics! No car damage? It looks deep.No Mr. Anderson, and thanks for asking. I did see some steam at one point but it was very brief (maybe 10 seconds). I was not in what the pictures showed, but maybe 50 feet away at higher ground. The trick was finding intersections with no more than 6" or so and manuevering through them. It definately got scary, especially in light of the "Jedi Intake trick", but she did fine.

[TSi+WRX]

Nice rain pics! No car damage? It looks deep.

And all:

Here's yet another water-crossing tale, posted originally on .com by brother Prod


I don't recommend ever doing this. I won't do it again. An Outback would have been a better choice.

This was at Stony Fork Campground, the creek crossing was about 3" deep before it rained all night. I was up there visiting STPR with friends.

http://www.cse.psu.edu/~maynard/legacy_album/ (http://www.cse.psu.edu/~maynard/legacy_album/)

My car was the obvious choice to make the crossing. The other cars we had available were a Ford Contour, a BMW 325is, and a Celica All-Trac. The All-Trac only had 2 seats and was not conducive to us going spectating.

Ok, so I had no idea it was that deep going in. I slept in, and my friends told me that a minivan made it through. But the minivan did it about an hour earlier, before the water rose to that level. They failed to tell me that a new Tahoe didn't make it. About half an hour after me, a Jeep Grand Cherokee went for it and hydrolocked. I thought we were done when the water came halfway up the windshield. The engine kept turning, so I kept going. When we were almost to the other side, the car started drifting to the right a little. I corrected and we got ashore safely. Yeah, I got lucky.

The car had a rough idle, so I shut it down. We took out the air filter and naturally it was soaked, but the car ran fine with it out. A few minutes on the camp grill and the air filter was dry enough to use again. The car ran like a champ while we went to 5 spectator sites during the day. It also had no problem with the 300 mile journey home the next day.

+1 for Subaru!


Notice this was a Legacy :eek: - and that he admits to (1) this not having been a great idea from the outset and (2), that an Outback would have been a much better choice under the circumstances.

I'm again not saying that any of us should be doing this, "recreationally," but it's good to know that when/if an emergency ever arose, that our LGTs are so friggin' capable! :tup:

[Effin Ponderous]

Wow, I thought I had it bad!

[Effin Ponderous]

This "waking up at night with ideas for the LGT" is becoming obssesive to say the least, but I got an idea that I wanted to throw out here.
I've got this opening at the bottom of my intake housing now that certainly creates a new tone upon acceleration. I read some posts where people threw out the idea of runing a hose to bring in cool air. Unfortunately, the only cooler air brought in would be while moving (at best) and we already have the intake duct to accomplish that.
I was at a marine parts store this morning to pick up something for my buddy when I spotted a bilge evacuation blower. They had one on the clearance table so I grabbed it. My thought is, if I can force cool air in at a high rate it should help reduce intake temps and increase overall performance. Am I suffering the effects of sleep deprivation, or does this have any merrit?

[Drift Monkey]

This "waking up at night with ideas for the LGT" is becoming obssesive to say the least, but I got an idea that I wanted to throw out here.
I've got this opening at the bottom of my intake housing now that certainly creates a new tone upon acceleration. I read some posts where people threw out the idea of runing a hose to bring in cool air. Unfortunately, the only cooler air brought in would be while moving (at best) and we already have the intake duct to accomplish that.
I was at a marine parts store this morning to pick up something for my buddy when I spotted a bilge evacuation blower. They had one on the clearance table so I grabbed it. My thought is, if I can force cool air in at a high rate it should help reduce intake temps and increase overall performance. Am I suffering the effects of sleep deprivation, or does this have any merrit? Air is already being forced into the motor...with the turbo charger! :lol: Seriously though, I'm not sure if this will help much, you might want to look into ways of cooling the air AFTER it goes through the turbo...aka larger intercooler, alcohol injection, etc...

Trust me, I understand the sleep thing. My sleep cycle is seriously fux0r3d. I didn't even really sleep last night. :mad:

[Effin Ponderous]

I just thought that if you are sucking hot air to begin with, it's hotter inside.

[Drift Monkey]

I just thought that if you are sucking hot air to begin with, it's hotter inside.
The thing is, I'm not sure of that the blower will lower the temperatures to a signifigant amount. The only way to truly test it would require sticking thermometer sensors in the intake and running with/without it to see if there is a signifigant drop. If you got the time to do it'd like to see the results! :lol:

[TSi+WRX]

^ Or datalogging. The Intake Air Temperature (IAT) would do. ;)

I've actually "hung" a temperature sensor in this area as well as datalogged IATs. Typically, IATs are within 5 to 10 degrees of ambient - with the IAT being on the hotter end.

Our stock airbox is *AWESOME* at insulating the intake air, as well as allowing for incoming ambient air to be properly ducted to help lower IAT as fast as possible.

I have yet to play with this area on my LGT. I just haven't had the time. So far, I've only fab'ed a home-made full heat-shield for my Perrin Short Ram, out of laboratory/autoclave-grade thermoplastics and quite a bit of Thermo-Tec insulating tape (the thick kind).

However, on my old DSMs, I always similar crafted "cold air ducting" to what brother Effin cited.

And while I truly do not know (nor think) it much affected power (it was *not* butt-dyno-able), I can say with certainty that it does contribute tremendoulsy to lowering IAT and "intake area" temperatures as soon as any decent forward motion is had by the vehicle.

Think of it as our stock intake "snorkel," only drawing air from an even cooler location - and, depending on how large of an opening you've got, perhaps a even larger "funnel."

-----

So.....this is a question that's bothered me for a while.....

It's known that our ECU factors in IAT - the temperature at the MAF - into its magic-brain equation of how much timing it will allow us to run. This, of course, translates directly to how much "power" we have on-tap.

Now, then, my question is this:

Do we also have a sensor which reports the actual CHARGE TEMPERATURE (temperature after the heated intake charge passes through the intercooler, and is seen at the throttle-body junction) ?

I have yet to find this parameter in any free datalogging software.....

If not, and if how the ECU "judges" timing is only noted for IAT, then wouldn't it indeed be to our advantage to try to truly get IAT as low as possible?

And if there's no charge-temp. sensor, then how in the name of heck does a "better" intercooler help to make our car perform better? It's been proven that a "better" intercooler does contribute significantly to both peak power as well as the powerband itself, but how is this reconciled with the IAT *as referenced above*?

Questions posed for all.

Any and all advice/speculation/opinions are welcome. :)

[Drift Monkey]

I don't believe we do have a sensor for intake charge temps, I think all readings/adjustments are made soley by the MAF.

Cooler air just means more air, and I don't think the ECU compensates timing for this. It usually is concerned about the A/F ration and fuel grade..

More to add later, I'm hungry, need lunch..:lol:

[TSi+WRX]

Go feed your brain, then hurry back! :D

[Drift Monkey]

Go feed your brain, then hurry back! :D OK, back. Did some more thinking/researching, and I think I figured that the MAF is the only sensor it needs in it's current setup. The MAF on our cars measure air MASS. With a cooler intake charge and the same MAF readings you still get the same amount of air in the cylinders. Even if the charge is cooler, air going past the MAF = air going into the cylinder. Even though pressure, density, and temperature changed, mass stays the same. If we chill the intercooler, and the air gets more dense, and the engine uses more mass than is passing through the MAF, then a vacuum is created, more air flows through the MAF, and the system balances in milliseconds. While our cars do not have an intake air tempurature sensor after the turbo like some other cars (ours is built into the MAF), it can calculate the manifold air temperature basied off the MAF and MAP, combined with engine volume and rpm. This lets it judge the quality of the incoming air and, in combination with a bunch of other factors, and pick proper ignition timing from the map. So if your intercooler is heatsoaked from siting in traffic, the ECU will immediately pull timing because your intake charge is hot - it has a spot on the timing map for that hot intake charge. This is to keep detonation from occuring. This is also why the stock ecu can also handle a turbo and intercooler upgrade, on stock bost control and fuel - all you are doing is blowing cooler air.

[Effin Ponderous]

so then if we duct cooler air in (forced), wouldn't there be a positive effect especially when the car is stuck in traffic and there's no ram air effect?

[Drift Monkey]

so then if we duct cooler air in (forced), wouldn't there be a positive effect especially when the car is stuck in traffic and there's no ram air effect?
I'd have to say no. The turbo will stuck in that air and spit it out HOT. You'd be better off having that fan blowing on the intercooler. Maybe you could do a water spray system on yout TMIC?

[TSi+WRX]

^ Exactly - if you're truly stuck in traffic or sitting at that infamous 4-minute traffic light right by where I live, you're SOL. Your TMIC will heat-soak, and then it's hotter air all the way. You'll literally be able to feel the car pull timing.

But if you're speaking of anything outside of heat-soak, then yes, it might help a little. Exactly how much you gain, though, especially without a tune to specifically take that into account, is more than likely negligible.


-----

RE: IAT vs. Charge Temp.

DM - That's very thoughtful, bro, and I'm inclined to agree with your reasoning. Thanks for putting it out there, as well as for your deductive effort. I just couldn't quite wrap my mind around it ( although, in a "moment of clarity" while feeding baby Anna her mid-night feed at around 3AM this morning, I *almost* reasoned it all the way through :lol: ) !

:D

[Effin Ponderous]

Ok...back to the drawing board.

[TSi+WRX]

Here's what Christian at Cobb had to say about this:



Originally Posted by TSi+WRX http://legacygt.com/forums/skynetim/buttons/viewpost.gif (http://legacygt.com/forums/turbo-powertrains-2-0gt/39773-per-your-request-extensive-post708204.html#post708204)
^ I've been wondering about this....
It's cited (both on this thread and many times elsewhere) that our ECU bases some of its timing "judgement" based on IATs, correct?
Do we also have a sensor within the vehicle for the actual charge-temp, and does the ECU compensate accordingly?

No, the vehicle does not have a charge temp. sensor, just an IAT at the MAF sensor.


Originally Posted by TSi+WRX http://legacygt.com/forums/skynetim/buttons/viewpost.gif (http://legacygt.com/forums/turbo-powertrains-2-0gt/39773-per-your-request-extensive-post708204.html#post708204)
Or is the ECU basing things off the IAT as a good method of inherent fail-safe?
http://legacygt.com/forums/images/smilies/icon_confused.gif http://legacygt.com/forums/images/smilies/confused.gif

The engineers whom establish the ECU calibrations figure out the mechanical efficiencies of the chosen intercooler and establish their calibrations based on their research and findings.


Originally Posted by TSi+WRX http://legacygt.com/forums/skynetim/buttons/viewpost.gif (http://legacygt.com/forums/turbo-powertrains-2-0gt/39773-per-your-request-extensive-post708204.html#post708204)
And if the ECU sees only IAT, but not charge-temp, how, then, does an aftermarket TMIC - or *any* intercooler, for that matter, help contribute to better performance?


A good intercooler is able to bring down the charge temperature to close to 30-50 degrees above ambient temperatures if it has been matched well and the turbo is still running within its efficiency range. You can usually see (datalog, use external sensors, etc.) how a vehicle reacts through dyno and road testing.

Take care,
Christian.

Christian's replies are in bold and highlighted blue to ease readability. I did not change his text nor wording.

Basically, like DM speculated, it's the computer doing its magic via an algorithm, and our only temperature sensor is at the MAF.

[Drift Monkey]

Here's what Christian at Cobb had to say about this:



Christian's replies are in bold and highlighted blue to ease readability. I did not change his text nor wording.

Basically, like DM speculated, it's the computer doing its magic via an algorithm, and our only temperature sensor is at the MAF.
I knew it. ;)

[Effin Ponderous]

OK guys, beat me over the head for this one, but:
If the ECU takes air temp at the MAF, and you could somehow lower the temp 30 or so degrees at the MAF, what would the ECU change based on lower intake temps? Does it raise or lower AF mixtures based on the density of the incoming air? If so, wouldn't this have to change something pretty significant? Maybe my density is too high here?

[TSi+WRX]

^ No, no, your density is definitely just fine, bruddah! :lol:

From my perspective, yes, cooling the intake-area temps as much as possible should help plenty, but we've still got to keep in mind that even if you're cooling the IAT to-ambient via various ducting/fans (useful, say, if you're sitting at that year-long traffic light), your heat-soaked intercooler is not going to be properly cooling that first bolus of charged air, and that the vehicle itself, from pre-programmed algorithms which would likely signal a "hey, I've been idling for, like, the past 5 minutes" kind of a situation, would still pull timing accordingly.

If you're on the road doing 35+ MPH, or if you're running that fan because you're in some city-traffic, then yes, you'll probably do some good - at least that's my base belief. ;) As long as there's airflow to cool both the intake air temperature (which, in this case, will be helped by the home-brew setup) and the intercooler is not heat-soaked, you're probably seeing some benefit from that kind of setup.

And yet again, the question of how much would this help rises up....

Honestly, I don't know. I'd imagine that if it's something that actually can be tuned for, its returns might be substantial enough that it can be butt-dyno-able (but considering the types of situations under which such a gadget would return "gains," would you really want it to be tuned for such? or would you rather keep it as a simple "fail-safe" kind of device, adding to your tune's inherent safety factor? my preference would be the latter). But from my past experience, I know that just "grafting on" such devices pretty much nets no discernable gain in the "butt dyno" department, although the air-temperature benefits *are* clearly visible on a truly quantitative basis.

[Effin Ponderous]

OK, I think I'm getting it now (and again, sorry for the redundance). What you are saying is that it's not so much the hotter air that gives the bad performance, it's the computer thinking there is hot air (and making adjustments) that does it. If that's the case, there's not a helck of alot that can be done without reprograming.

Ah Crap, then wait a minute...why would throwing a bag of ice on the IC make any difference in performance?

[Drift Monkey]

Ah Crap, then wait a minute...why would throwing a bag of ice on the IC make any difference in performance?
Yes. In fact, I usually throw slabs on dried ice on my IC when I'm at the strip (which is very rarely).

[TSi+WRX]

^ Good question, brother Effin :) - and quite frankly, I don't know.

This is something I need to ask, and surprisingly ( or rather, not so, as I haven't really been able to make proper change at the grocery store since Anna was born :lol: ), totally forgot about.

Indeed, like brother DM said, it's quite true in the real-world that "icing your IC" will produce excellent results - both on the strip as well as on the dyno. Reducing charge-temp really does work.

And as brother DM speculated before:

If we chill the intercooler, and the air gets more dense, and the engine uses more mass than is passing through the MAF, then a vacuum is created, more air flows through the MAF, and the system balances in milliseconds. While our cars do not have an intake air tempurature sensor after the turbo like some other cars (ours is built into the MAF), it can calculate the manifold air temperature basied off the MAF and MAP, combined with engine volume and rpm. This lets it judge the quality of the incoming air and, in combination with a bunch of other factors, and pick proper ignition timing from the map.

Which, to-follow, while he later cited the example of heat-soak, it would thus also reason that the "natural balance" struck by the cooler air now resident within the TMIC/post-charge would give the MAF new data - and thus give us slightly more power when the IC is "cooled."

This is often why you'll see such IC "icing" at the strip (be it bags of ice, slabs/pieces of dry-ice, or even using a dry-ice/alcohol "slurry" in their air-to-water intercoolers) - or people who use either a water-sprayer or CO2 (or even nitrous) sprayer on their ICs right before/at-the-start-of a run.

[Effin Ponderous]

I think it's time to get the hoses and start some testing. Supplying cool air to the air box will be the easiest thing to start with.

[NALegacy]

I think it's time to get the hoses and start some testing. Supplying cool air to the air box will be the easiest thing to start with.

I think I'm going to tackle the ghetto intake mod on my car...saw that thread over on NASIOC, and it's got me thinking:p

[Effin Ponderous]

I think I'm going to tackle the ghetto intake mod on my car...saw that thread over on NASIOC, and it's got me thinking:p
What is that?

[RX300T]

for discussion sake, wondering if it's better to seal the hole after removing the silencer? cos i sealed mine, thinking that it is actually used to resonate the sound and not to introduce air. with the car moving at speeds, the pressure difference in the air coming in from the hole and the air duct mught cause a vaccum effect.

my $0.02 worth.

please comment and advise. :o

[Effin Ponderous]

Haven't noticed that at all a year or so later.

But on another note...I put in my K&N filter over the weekend. While I don't notice anything on the butt dyno, I can actually hear my stock BOV now!

Woohoo, rice-a-rony!

[Drift Monkey]

Haven't noticed that at all a year or so later.

But on another note...I put in my K&N filter over the weekend. While I don't notice anything on the butt dyno, I can actually hear my stock BOV now!

Woohoo, rice-a-rony!
A San Francisco treat!

[ih8vtec13]

for discussion sake, wondering if it's better to seal the hole after removing the silencer? cos i sealed mine, thinking that it is actually used to resonate the sound and not to introduce air. with the car moving at speeds, the pressure difference in the air coming in from the hole and the air duct mught cause a vaccum effect.

my $0.02 worth.

please comment and advise. :o

I dont think it would really matter if you sealed it or not, I ran mine of for about a year and was fine. I would look into a panle filter of some kind and use that over stock. I think that the hole open may casue the car to get a little more airflow colling it.

[RX300T]

thanks, i'll try to leave the hole open and see if there is any difference. maybe even fabricate a CAI from flexi hose/tube to draw air from the front. :)

[NALegacy]

thanks, i'll try to leave the hole open and see if there is any difference. maybe even fabricate a CAI from flexi hose/tube to draw air from the front. :)

I've been wanting to do this. But I'm too lazy.:lol:

[Drift Monkey]

I've been wanting to do this. But I'm too lazy.:lol:
It won't make a noticable difference I don't think...

[RX300T]

was trying to figure out a way to keep the fogs and no cut the bumper but can't seem to find an opening beside the radiator to position the cold air piping. will see what i can do cos i suspect the plastic piece beside the radiator can be removed.

[TSi+WRX]

for discussion sake, wondering if it's better to seal the hole after removing the silencer? cos i sealed mine, thinking that it is actually used to resonate the sound and not to introduce air. with the car moving at speeds, the pressure difference in the air coming in from the hole and the air duct mught cause a vaccum effect.

my $0.02 worth.

please comment and advise. :o

^ I honestly don't know, and you're right, it is something that should be examined.

The only thing that struck me as somewhat "strange" is that a lot of the Open-Source tuners do specify whether or not they have a "sealed" stock intake-box modification - i.e. whether or not they've taken care to seal the open hole after resonator/silencer removal.

This leads me to think that there's some effect - but how it may present in terms of real-world differences, I honestly don't know. :o

I've never datalogged the different possible setups........

[sspeed]

When the intake silencer is removed and the stock airbox left intact, is the BOV noise brought out as well or is that still pretty non-existent?

I liked the BOV noise on the Talon, but don't want it on the Legacy, I just want subtle turbo spool noise.... I was thinking of removing the black box intake silencer for the general intake and putting a small one in-line on the BOV return hose... What are your thoughts on that? Any other ideas?

[han]

I dont know about the return hose thing, but removing the intake silencer can has the added the wasgate sound louder.

[Dookie]

Meh.....Just keep the intake silencer on in that case. What's the purpose of taking one off, just to add another one?

[TSi+WRX]

I agree with the others, I honestly don't know about putting a resonator back.....

You should get a bit more audible feedback from the "intake loop," but you'll want a freer-flowing aftermarket panel filter to best bring-out that trait.

And if you want to hear the actual turbo itself, the best way to go is to actually do the aftermarket UP and DP mods.

Increasing boost levels to above-factory will also tend to bring out wastegate flutter sounds.......

[Maddie08]

Took out the silencer, it's kinda cool. I would estimate the 2000-4000 rpm noise is increased by 100% and is much deeper. The turbo spool by 10% through the range. Wastegate by 25%. High up revving maybe 5-10% increase in noise.

Good mod, I wanted a Subaru not a Lexus (The car is quieter than the IS 350 from my experience).

Bump! And thanks for the walkthrough, it literally took 10-15 minutes in the AutoZone parking lot.

[blk2.5GT]

I just took of my SPT intake and heat shield off to do this mod because the SPT is crap. I took the silencer portion off. Am I suppost to cover the hole at the bottom of the box that lead into the silencer? I ran my AP and now I'm only at 13.6 PSI compared to 16.4 PSI with the SPT intake...wft? I have not reflashed yet. Thoughts?

[TSi+WRX]

Are you comparing boost on similar days - the heat/humidity will affect our ECU's determination of how much boost the engine can safely take.

I'm a typical "Stage 2," and my max boost is 19 PSI...in the dead of winter. In the worst of the heat and humidity of summer, I can be down to only 16 PSI. You'd put up your post yesterday, and I was outdoors in a shooting class all day, so I know first-hand how horribly hot and icky it was. :lol:

Other factors can affect boost, too, and unless you've datalogged, it's virtually impossible to say why things are "off."

You say that you haven't reflashed - that you're still on the same map as you were on, with the SPT intake in-place? Were you tuned specifically for the SPT? If so, then that's a problem, right there. If not, it's well possible that your ECU is trying to adjust for the sudden switch in hardware and the airflow differences that it suddenly sees.

Regarding the silencer/resonator and the hole, different people have different opinions about this. Some say that it's not necessary to even account for its removal - yet others say that it can affect intake-tract properties enough that it should be accounted for. Some prefer to seal the hole, for this reason, yet others utilize the hole to either "home-make" a cool/cold-air duct for it, or, alternatively, close it off.

[blk2.5GT]

I am still on the same stage I 93 map that I was with the stp intake. I never had a tune done to the car, just the normal stage I AP reflash. It was in the upper 90s when I first ran the car after reinstalling the stock box. Today I ran the car still unflashed with the stock box the and it topped out at 15.1 psi. It was cooler today however. What intake should I get? Im think of getting the K&N or the Perrin.

[TSi+WRX]

Ah.... :) It looks like it could be a combination of things, then - that your car had adapted, as much as it could, to the SPT, which the factory intake then threw it off its learning when you'd popped it back on without resetting the ECU; as well as that it was just uber hot and muggy, which doesn't help with heat-soak.

I'd let the car get used to the transplant for a couple of days - or reset the ECU and let it re-learn its way back.

The Cobb "Stage I" map, off-the-shelf, was never meant to accommodate for the behaviors of the SPT SRI. Strictly speaking, Cobb's recommendations are for absolutely no alterations to the intake tract, when running their AP's off-the-shelf maps.

[blk2.5GT]

When you say resetting the ECU, you mean a reflash with the AP right?

[TSi+WRX]

^ Nope, just a reset. :) There should be an option for "ECU Reset" on the AccessPORT (or virtually any other datalogger device/program), or, alternatively, you can use a simple AutoZone/AdvanceAuto-bought $40 "code-reader" that you use to read CELs (actually, DTCs ;)), and simply as it to "Clear Codes."

The final alternative is to unplug the battery negative and pump your brakes until you can't see the brake lights turn on any more (to discharge any residual charge in your electrical system). That'll also reset your radio stations, though. :lol:

After the ECU reset, the IAM should go back to whatever it was pre-set to be, and your car will then start to "re-learn" everything.

[blk2.5GT]

Ohhh ok. I did a few strong pulls when it was 65 with low humidity, and the best was 15.6 psi. I actually think tha the spt intake was making more psi than the stocker I put back on. Im going to do what you suggested. After that comes the reflash correct?

-Robert

[TSi+WRX]

Ohhh ok. I did a few strong pulls when it was 65 with low humidity, and the best was 15.6 psi. I actually think tha the spt intake was making more psi than the stocker I put back on.

It's possible, but again, it's hard to say with-certainty, given that your car is probably still "learning" its way back.


I'm going to do what you suggested. After that comes the reflash correct?


Sorry, but I'm not following...:o What's "that" that you speak of? :confused:

[Dookie]

Possible boost leak in the intake? Every once in a while I would need to tighten the fittings connecting to the TMIC. Secure all connections 1st before you reset, just to be on the safe side.

[blk2.5GT]

Oh, I was just saying I'm going to reset the ECU like you said and after that comes the reflash. Correct?

[TSi+WRX]

Possible boost leak in the intake? Every once in a while I would need to tighten the fittings connecting to the TMIC. Secure all connections 1st before you reset, just to be on the safe side.

+1. Definitely do this - great catch, Dookie! :tup:

Oh, I was just saying I'm going to reset the ECU like you said and after that comes the reflash. Correct?

In all honesty, it looks like your car is learning itself back well enough. Without datalogging, we'll never really know, but given that boost "keeps coming back," I'd be willing to just let the car run for a couple more days.

When you reflash, you'll essentially be resetting the ECU, so there's no need to do that, prior. :)

[blk2.5GT]

Sounds goods, thanks for the advice...you guys are awesome!

-Robert

[Dookie]

Speaking of boost leaks, I just blew my intake hose off again last night. I felt a drop in power driving home and then notice I was only running 8 psi of boost at WOT. Need to find some better hose clamps.

[blk2.5GT]

That sucks

[Dookie]

Sure does, like I sad before, it happens every once in a while. I jinxed myself with my previous post. :( :lol:

[Dookie]

Found out I didn't have a leaking hose, all hoses were secured tight. There were no codes, just a loss of boost psi by 50%. Then I thought, "great it's either the BPV or the Turbo going out".:( Pulled the BPV out to inspect it, pressed on the valve and it seemed tight and in good working order. Before I decide to pull the DP off to inspect the Wastegate, figured I reset the ECU (OBDII reset) as mention by TSI. Thank god I did, as it did fix my boost issue. Boost is now back to normal. :tup:


Funny how my car developed the same issue during the same time as this discussion. :o :lol:

[TSi+WRX]

^ Dookie, did you datalog, or manage to look at the IAM before you reset?

The reason I ask is because if your IAM falls low enough (for whatever reason), it'll pull boost down to wastegate only (which would be "about half" of what a "Stage II" car might otherwise see).

And if the IAM fell, then you need to find out why........ :(

[Dookie]

No I didn't datalog before I reset. Was going to datalog only if the reset didn't work and have Infamous1 take a look at it. I'll remember to do this next time if/when it happens again. That was strange though, I've been running Stage I for 2.5 years now with no issues. But then again, the car just broke 100k miles a few weeks back, so I guess it's time to prepare for somethings to go wrong.:o

[blk2.5GT]

Ok, I'm thinking that this thread is cursed. A few days ago I took off my SPT intake and put my stock airbox (minus the silencer) back on the car. Yesterday, I noticed the car was making a high pitched shreeking noise (like a damn bottle rocket) starting around 3,500 RPM's under moderate acceleration. I thought it might just be the turbo since I took the silencer off. On my way to work, the car lost about 50% power. I hooked up the AP and ran the live boost option and it read 12.8 PSI. The car doesn't even feel like its running that. It's like the turbo is spinning and not making any boost at all. I popped the hood and check the hoses and clamps but didn't find anything that was loose. I reflashed the car today before this happened, but the shreeking noise started yesterday. WTF??!

-Robert

[TSi+WRX]

^ Something is leaking - that banshee's wail is most likely some kind of mating surface that didn't go back together correctly. The car can actually achieve target boost with a *huge* leak in the pre-turbo part of the tract (i.e. if you've got 2 of three of the manifold-to-UP bolts totally lost, and the 3rd one is loose! :o :lol:).


-----


Dookie, definitely look at the IAM first, next time. :)

[blk2.5GT]

A co-wroker of mine has a WRX and said he had the same issue. His was the sensor in the DP blowing air out. We took a look at that and it was a little loose. Took it out for a test drive and the scream turn into an elephant sound (yep). We inspected the engine and found that a few of the clamps were loose, with one almost completly off. We tighten them and ran the car again. I hooked up the AP and boost is running at 15.4 psi. The car is running great now! (Knock on wood)

-Robert

[Dookie]

Cool, glad you found it. I remember when my UP came loose, it sounded like I was driving a loud whistle down the street.:lol: Yup, those boost leaks can be a beotch for the 1st few times until you know the different sounds they make. Then you'll be able to pin point it next time.



TSI - I most certainitly will check it next time, thanks!:)