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Guest Message by DevFuse

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I implore everyone....DO NOT put an open style intake on.

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26 replies to this topic

#1 Guest_Legacy777_*

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Posted 01 May 2002 - 08:43 PM

As some of you know.....I've been trying to find the reason behind my high idle issues. Well I've narrowed it down to what I think the cause is, very small vacuum leak. Why do I think this, when you first start the car up after it has been sitting, and you put it in gear, or put the A/C on, ie: load on the engine, there is a very faint whistle. Now all I have to do is find the little bastard.

So....I decided I'm going to clean the gook and grease out of the engine. It's caked up around the valve covers and base of the intake manifold. There's only so many places there can be a vacuum leak. I think it's coming through a gasket.....just don't know which one.

In preparation for the engine cleaning. I put the stock airbox back on so I can spray the engine bay. I had been meaning to do this for a little bit....but just haven't gotten to it because of the idle issue.

Well let me tell you something!!!! The car purrs like a @$@#in kitten.....the idle used to bobble up and down when the fans kicked on.....and such.....it's still higher then normal....but it is smooth.

There are two things I contribute to this. One is the suction of "cool" air from the fender. Two.....the metal plate or bracket that is inside the stock airbox that connects the box to the MAF is actually a nozzle...or some form of one.

The edges flare out, and then roll inwards to where the MAF is. With this, you help increase velocity as air is entered into the MAF.....also at the edges it helps smooth out the turbulant "boundary layer" air. All of this helps the MAF more accurately measure airflow.

Other results.....the dead spot or "bogging" is much less pronounced....I need to reset the ECU....especially since I have been yanking sensor wires to see what happens when they get pulled.

I don't think it pulls as fast in the higher revs as it did with the funnel filter......however I plan on remedying that.

I'm already running a K&N drop in panel, so that helps flow. Next I am going to get a 90 degree elbow in PVC, and mate it to the bottom of the filter box. I'll pipe this into the fender well, secure it and do some sort of rubber type seal like the OEM tube has on it. I'm also goin to drill out the rivets that holds that little plate with the rubber seal on it, so I have a bigger inlet for air, and again will rig up some sort of rubber type seal.

I am hoping that with the addition the extra intake tube and larger intake tube, it will be able to flow as much air or around the amount of air as the open style filter element.

Also I'll probably look into wrapping the intake tube with some sort of thermal wrap to help keep the intake charge "cold"

I'll try and take a pic of that nozzle looking thing if I'm monkeying around with stuff this weekend or some time, so you can see what I'm talking about.

#2 Guest_Legacy777_*

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Posted 01 May 2002 - 08:56 PM

wow.....just saw a pick of the inside of a stock box on a newer gen subie......it does not have the nozzle I was telling you about.

here is a pic of it.

Posted Image

#3 Guest_newbie boater_*

Guest_newbie boater_*
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Posted 01 May 2002 - 08:59 PM

Well hells bells. I have been thinking air leak the whole time, but didn't realize you had a "fancy" air intake system. If I read your post correctly, there was an air "cone" "directional modifier" on the factory setup that wasn't there in the aftermarket one? That MAF sensor is VERY picky as to what it sees. I think you have a DVOM, hook it up to the output wire on the MAF with the key on, engine off, or even engine running, and just get enough access to it that you can blow across the sensor with your mouth. Watch your readings change!!! A little blow goes a long ways, I hope this is truly your culprit, makes sense to me, keep us posted!!!!

#4 Guest_SmashPDX_*

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Posted 02 May 2002 - 12:22 AM

Yeah that thar fancy intake thing can mess up a whole mess of vacuumin' yep, mmm hmm, yep.


#5 Guest_Legacy777_*

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Posted 02 May 2002 - 07:29 AM

The fancy intake is not the culprit.....nor is the MAF sensor.

There is a vacuum leak downside of the throttle plate. I am thinking a gasket, as there just really isn't alot if any vacuum lines on my car.

I have swapped out the current MAF with the old one I had, and I still get the same high idle....so it is definitely no the MAF. And the idle is so high now....that the IAC valve is practically closed.....I'm not really getting any flow through it. I do get a fairly strong vacuum if I leave my hand over the intake hose for it.....however the part I don't get is why the car doesn't really change how it runs when I pull the tubes off....ie more air would be introduced since the tube is off and it's sucking in air post MAF......I don't know.....I gotta deal with it one step at a time.

I'll try and get a pick of that piece on the stock intake box.

As for performance/driveability. This morning I could feel a difference.....it definitely did not pull as strong as it did before through the RPM range. I really contribute this to the small diameter of the intake tube goin to the box.....but like I said I'm planning on correcting that.

Also the "dead" spot or hesitation seems less noticeable....the RPM and throttle response is definitely different...can't say whether good or bad....it's just different....especially after driving it that way for a while.

When and if I find the stupid frontal area for my car....I will run the Road Dyno and get a comparison between the stock box, and the open style intake.

#6 Guest_Gus_*

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Posted 02 May 2002 - 07:52 AM

Have you performed the old starter fluid method of finding the suspected vacuum leak? ;)

#7 Guest_Lustreking_*

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Posted 02 May 2002 - 08:00 AM

>When and if I find the stupid frontal area for my car....I will run the Road Dyno and get a comparison between the stock box, and the open style intake.

If you're just doing comparitive runs who cares about the frontal area? As long as you use the same number for each run everything should work out.... just don't compare it to other cars, just itself


#8 Guest_Legacy777_*

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Posted 02 May 2002 - 08:07 AM

well I would like to try and get a reasonable number.....I know i can get do comparitive runs no prob.....but I WANT THAT DAMN NUMBER!!!!

Dave....yeah I've tried that once.....I'm goin to clean the engine friday, and may try again if the leak doesn't jump out at me.

#9 Guest_Legacy777_*

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Posted 27 May 2002 - 08:36 PM

ok.....this is kinda late.....but better then never.

here are the pics of my stock box with the velocity stack on it.

Posted Image

Here is one you can get for an aftermarket intake.....probably work pretty good for a cobb intake setup.

It's from suby sports

Posted Image

I know this is a little old....but I thought the pics might help clear things up a little.

Also here's a thread over on i-club with pretty much same info and such, plus a little more


#10 Guest_SmashPDX_*

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Posted 28 May 2002 - 09:47 AM

Very interesting pic... I may have to pick up one of those jobbies used, especially since my intake just kind of, um, fell off (fractured support bracket, intake popped right off of the plenum). I repaired it, but I'm glad the engine died outside my house instead of on US 26... :)

#11 Guest_Legacy777_*

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Posted 28 May 2002 - 11:56 AM

So your weapon R just died and broke? or the brackets.......?

I'd really suggest you try to get something similar to the stock setup back on.....or something sucking from the fenderwell with a little more less turbulant supply of air.....

#12 Guest_SmashPDX_*

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Posted 28 May 2002 - 02:46 PM

Just one of the brackets. It was a pretty cheap install, nothing comparing to yours. Basically just had a long piece of metal, so flimsy you could bend it with your hands, anchored to the intake manifold via bolt and "anchored" to the Weapon-R tube via one of its clamps. Snapped next to the intake manifold.

I've been planning to yank the Weapon-R anyway, so that's the project du jour within the next couple of days.

#13 Guest_SUBYDAZZ_*

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Posted 28 May 2002 - 07:36 PM

Hey Josh do you have a part number for that flat panel K&N? I am trying to track one down now at the best price I can get. ;)

See if the newer GEN3 intakes will fit in place of the stock airbox, there seems to be a freer air path into the MAF. The early ones seems to suck air against a flat wall (as you can see in the pics). I will be fiddling around with this in the coming weeks.

Will Thermo-Tec-ing the air duct make much difference? After all that air rushes in pretty quick doesn't it? Wouldn't ahve thpought there'd be too much heat absorption going on there. I guess the only way to tell would be to comprehensively dyno with and without the mod anyway.

:) Posted Image :)

#14 Guest_SUBYDAZZ_*

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Posted 28 May 2002 - 07:41 PM

Re: velocity stack:

Is that rim around the MAF intake on the GEN1/2 pic an aftermarket fitment? Is this what you call a velocity stack? In that application it would appear that it would probably be more of a hinderance to airflow than a help, in the later GEN airbox however...

:) Posted Image :)

#15 Guest_Legacy777_*

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Posted 28 May 2002 - 09:56 PM

No....a velocity stack or nozzle is the thing that helps smooth and speed up the air going into the MAF.

Basic principles of a nozzle are that if you take a certain amount of substance and cram into a smaller space it must increase in velocity. Atmosphere.....or the air in the air box is considered an infinite volume.....the nozzle or velocity stack helps channel that air into the MAF more smoothly, and produce better laminar flow characteristics at the MAF so air reading will be good.

As for the panel number.....I'm not sure....the box I got it in was a box for the WRX filter.

The thermal wrap will help. Meep did it to his 95 I think, and he said it did help.

As for the first gen's sucking air from a wall right behind the MAF......you're not moving enough volume of air to have that be a problem. The opening is plenty sufficient.

Maybe if you're running 30 psi of boost....then maybe yah that would be a restriction......but your motor would probably be flying too.

Biggest restriction in the intake system is the inlet into the stock box. Make that bigger, or add another....or both.....and that is no longer your bottle neck.

#16 Guest_Hondasucks_*

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Posted 30 May 2002 - 01:19 AM

Ahh Good Ol' Weapon R.. Makers of fine license plate frames and performance sticker kits :lol: :lol: :rollin: :lol: :lol:

Can't tell ya how many Honda's I've seen with "Weapon R" stickers but STOCK INTAKES lol...

#17 Guest_naliberty_*

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Posted 30 May 2002 - 01:57 AM

Subydazz, you'll understand this, but the US guys won't! :)

The K&N filter that fits our liberty's is available on the shelves at any K&N stockist!
Why you ask....... Because it's the same as a commodore one! :D

#18 Guest_SUBYDAZZ_*

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Posted 03 June 2002 - 08:36 PM

Yes I thought so. I was jsut trying to clear something up. I assume the part number is KN33-2031-2 or KN33-2031-1 or KN33-2032. Which one is right, or are all of them right?

:) Posted Image :)

#19 Guest_TinyClark_*

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Posted 07 June 2002 - 03:57 AM

I see a lot of different ideas about intake improvements on the Sub's, but will probably try to do something about the exhaust on my weak 2.2 Legacy.

I was just wondering what good all that stuff does with that thick mesh screen standing in the way of the incoming air, and if anyone has tried removing that as well.

#20 Guest_Legacy777_*

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Posted 08 June 2002 - 09:01 AM

I wouldn't remove the mesh. It's there to help protect the MAF, plus it helps diffuse the air entering the MAF.

#21 Guest_SmashPDX_*

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Posted 08 June 2002 - 12:49 PM

Ya, needs protecting. Way too many stories of blown-out MAFs. That thing is a lot more sensitive than it looks and Josh here is the board expert :)

#22 Guest_PaganQWA_*

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Posted 09 June 2002 - 11:35 AM

I picked up the upper air box on a '93 Legacy EJ22 N/A. It has a slightly diffrent looking MAF and has teh velocity stacker.

Will this plug directly into my '90 EJ22 N/A wire harness and run properly? Should I just swap in the velocity stacker?


#23 Guest_Legacy777_*

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Posted 09 June 2002 - 02:44 PM

should fit......don't see why it wouldn't......how is it different?

#24 Guest_Legacy777_*

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Posted 25 June 2002 - 08:39 PM

I'm goin to throw this in the archives in a couple days unless anyone has any more to add.

#25 Guest_warlord_*

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Posted 25 June 2002 - 09:55 PM

hi josh.
there is a vacumetube running from the intake maniford (above on of the cylenders, i think its the front left)
this runs up to the vacume retard on the throttle.
on my car if you pull this off whoosh up goes the idle from normal to 2500 rpm.
hope this is helpful

btw i have an ej18 engine, with early style legacy intake box and set up (down drought style) running a k&n pod

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