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Discussion Starter #1 (Edited)
Cobb intake,,rattles?Solved

Ive had the intake on fr about a month now.Very satisfied with the performance.But one things kinda botherin me,I know there loud,that i got,but under semi to full wot it seems to rattle in the fender hole.Not a good sound ,my opinion.
Anyway,yes i used the collar that it came with and yes its on properly.and yes i have gas line split and suroundin the hole in the fender.My old ganzflo did it when i first got it, but i packed some foam around it and it went away.
I know the intake has gotta move some due to the engine moving under load but i was wonderin if anybody else has experianced this and maybe has a fix i havent thought of.
Ive tried the foam thing with this intake too,no go.
Thanks in advance
 

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engine mounts should help with that, or you can see if you can fab up a bracket that will make it not move as much.

or the cheapest thing to do would be to just cut the end where it rattles so it doen't touch any more
 

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I think it has more to do with the design... the flow is very high at wot, and the whole aluminum pipe resonates. It won't be pretty, but I'm considering wrapping my whole Cobb intake with header wrap to quiet it down some. It should also help keep the AL from absorbing heat from the engine compartment.
 

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I am planning on fixing that problem this weekend after I get back from snowboarding. It is either two things: 1. It could be that the pipe connecting to the throttle body is touching causing a rattle. Or 2. It could be the end of the pipe bouncing around in the fender well. Whatever it is I am going to find out how to fix it, because it is driving me crazy. I have STI engine and tranny mounts and that just makes the problem worse. Mine doesnt just appear at WOT it also appears at idle. You get lots of cool noises when nothing on the car shakes.:)
 

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yamarocket630 said:
I think it has more to do with the design... the flow is very high at wot, and the whole aluminum pipe resonates. It won't be pretty, but I'm considering wrapping my whole Cobb intake with header wrap to quiet it down some. It should also help keep the AL from absorbing heat from the engine compartment.
I have a better idea than the header tape, and it looks much better, and might even block more heat. I put Frost King Self-Adhesive Foil-Backed Foam insullation on my GanzFlow, and it almost looks like there is nothing on it. I just cut out strips to go around, cleaned the tube, and stuck the strips on. It's been about 9 months since I applied the insulation, and it's still on there. Here's a pic:
 

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Discussion Starter #8
Mine seems to settling in a little,but still there at times,,i dont think its the throttle body,i was all over mine lookin,and its not that bracket on the innner fender either,i bent mine wayouta the way.Its gotta be the pipe in the fender hole,,we just gotta find the right foam or rubber boot to dampen the vibration.Iwork at Home depot,im gonna go browsing theplumbing sec Mon.and see if i cant find somethin that will work.
 

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I just packed some foam around mine. It tends to stay in place fairly well.

That resonance/rattling at higher r'spm was annoying me. :boxer:

Something else I've noticed with the Cobb is that when you first touch the gas off of idle it makes a sucking sound. So there is a delay when you first get on the gas. I'm not crazy about this. I guess it's b/c there is no longer a plenum.


Aspen_2.5RS
 

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Aspen_2.5RS said:
I just packed some foam around mine. It tends to stay in place fairly well.

That resonance/rattling at higher r'spm was annoying me. :boxer:

Something else I've noticed with the Cobb is that when you first touch the gas off of idle it makes a sucking sound. So there is a delay when you first get on the gas. I'm not crazy about this. I guess it's b/c there is no longer a plenum.


Aspen_2.5RS
The sucking sound is the IAC motor opening, it has nothing to do with a hesitation or loss of the air filter box.
 

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:rolleyes:

Some of us non "ASE master mechanics" have no idea what an IAC motor is. Last time I checked the throttle plate was controlled by a cable.

Aspen_2.5RS
 

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Discussion Starter #12
Oh yeah,,I remember that!

Didnt Scotty once say,"We cant go to warp2 captain,the damned IAC motor wont open completly!!":eek:



I believe a further explanation is needed,,thanks;)
 
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My Cobb did the same thing. I don't think it's doing it anymore, since I sorta rotated it a little. The problem was that the intake was banging against a rear-brake thingy bolted to the strut tower. I have a shiny, eaten-away looking spot on mine now, and a matching one on a hose clamp on the upsteam side of the intake. I rotated the whole intake so it goes downhill more and misses that brake thing, then the end that sticks into the fender I rotated to keep it in the hole.

That should help a little. I'm also getting the STi Grp. N motor/tranny mounts, and that should take care of it completely.
 

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Discussion Starter #15 (Edited)
Thanks fr all the input,,,,

Well I finally got to HDR today(Home Depot Racing) and i think ive come up with a fairly good solution.
What i got was a plumbing connector, 3" in 3" out,,black rubber,with two large hose clamps on either end.FERNCO,PlumbQuick,part#P1056-33.
What you need to do is;Get the part,remove one hose clamp, you dont need it, Remove the Prm filter only and the small aluminum angled pipe with the red rubber sleeve that goes into the fender.Insert the Fernco pc into the fender hole with the end that does not have a clamp on it.Its kinda tite but it goes.Only put it inso far as it lines up with the indents were the clamp should have gone.Bout an inch.Loosen the clamp tween the bottom of the filter and the small al. pipe.Do not remove.Insert the pipe with the red collar and filter on the other end, into the Fernco pc thats sticken outa your inner fender.Push it in as far as you can.Then line up the filter with the red connector end that is attached to the al.pipe to the throttle body and push it back so it meets up and makes the connection.Some adjustments are needed to line the whole thing up.When you got it right ,,tighten down the hose clamps.
This quited down about 85 percent of the rattle fr me.It stiil has some harmonic rattles at wot.But it doesnt rattle at all fr normal driven.
Hope this helps
edit,the cost of the part is around $8.50 at Home Depot.I'll have dyno numbers available soon;)
 

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Intake noise

My first post!

Guys, I have had the PRM (cobb) intake on for a few months and the resonance/rattling was getting worse and very annoying. I have a '99 BTW. I also have a 90degree plastic elbow at the end of the intake inside the fender facing forward and slightly downwards. I decided to try stuffing fiberglass insulation in the fender. I put a whole bunch behind the elbow (opposite to the open end) and it made a HUGE difference inside the car!!! It is so nice and quiet now. I have put some in the rear quarter panels behind the plastic panels in the trunk and plan on putting more in the rear seat side panels. The stuff is very light and cheap. My only concern with the intake is that fiberglass particles are getting sucked into the air filter, clogging it up.... Give it a try, I'm sure it will help.

Luigi
 

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I took my Cobb apart today to clean and oil the filter. One of the pieces of foam I had stuffed into the fender had fallen down. It was sucked up by the intake. Luckily the filter is an ice cream cone shape so it wasn't sucked into the throttle body. I pulled the foam out and she's a bit louder now :).

Aspen_2.5RS
 

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Discussion Starter #20
Aspen,,that's what i was worried about when i was usin the foam.After i put the rubber piece on from Home Depot(see above fr part #) it just rattled a little.Now it's settled in and doesnt rattle at all.Try it youl like it,,looks good too.
 
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