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Old 07-15-2002, 10:38 PM   #1
scoobyguy
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Default Exhaust, Stromung issues 2002 2.5rs

I have Cobb CAI, Borla 3 gen headers, random tech cat, stromung intermediate pipe and stromung can. I am getting a poping sound when the car is under partial load and when I let off the gas... it is not rpm or gear specific. I cant tell if its just unburnt fumes ingniting or if there is some pressure issue... I have not double checked the gaskets yet.

Has anyone run into a similar situation?
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Old 07-15-2002, 11:38 PM   #2
spt_impreza
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the car does that wil normal crappy exhaust you just cant hear it.......the new exhaust just pronounces it more....no harm no foul..........in other words it supposed to do that.......(in robert deniro voice) dont worry 'bout it (end deniro voice)

spt
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Old 07-15-2002, 11:52 PM   #3
Cardwizz
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Where can I find more info on the Random Tech Cat??
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Old 07-16-2002, 12:18 AM   #4
quicksilver
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Random Tech makes two cats for our cars now. Gen 1 uses a ceramic, conventional shaped converter with a heat sheild. Gen 2 uses a new metallic converter that has no heat sheild. The converter itself is just a small lump in the pipe. I have prototype #2 of Gen 2 and it works great!! It's kind of loud, but sounds nice. Oh, you can get either from www.airbornemotorsports.com
I think Gen 1 is about $330 and Gen 2 is $410.

-Mike
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Old 07-16-2002, 02:26 AM   #5
Kostamojen
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scoobyguy: Its normal for aftermarket exhausts, even stock cars sometimes do it too (like AVATAR-X's 91 GTI)
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Old 07-16-2002, 04:14 PM   #6
scoobyguy
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I figured it was normal I just didnít think it would be so pronounced.... additionally does anyone know what the cause is.
I imagine, do to its irregularity, that it be a product of the relative pressure between the cycles of the engine. Is the actual sound an exhaust pressure wave suddenly filling a vacuumed space...

Anyway I am just trying to comprehend the mechanics.


~Chaise
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Old 07-16-2002, 05:03 PM   #7
ObsidianRS
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I don't know the mechanics of why, but the sound is caused by unburnt fuel in the exhaust system. The exhaust is hot and so the unburnt fuel explodes in the exhaust, creating that banging sound.

This is normal as said and completely harmless. From what I hear, it happened much more before computers in cars as when you let off the gas, much more gas is going through an engine that is not using it. Now, the computer is much better at quickly shutting down fuel to the engine when it's not needed.
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Old 07-16-2002, 05:24 PM   #8
Reciprocity
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From what I understand...and I could easily be wrong...but it is unburnt gas like the people above stated. And that pocket or bubble of gas is hitting the face of the hot cat and exploding.

It is extremely common in our cars. Personally I don't like it. Is it bad? I happen to think it might be...I don't think cats like little explosions.

NC
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Old 07-16-2002, 08:22 PM   #9
MrHorspwer
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I have a Stroumung setup on my 02 RS... does the same thing. It's normal. As an additional, some say that the recently released recall programming updates correct much of this condition. I don't know how true this is considering I haven't gotten a recall notice... just relaying some info along.
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Old 07-17-2002, 04:05 PM   #10
scoobyguy
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Waisted Fuel noooo.... shooting hp out the ehxaust...guess it doesn't matter too much since your not using that fuel to accelerate

Thanks for all your replies.

~Chaise
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Old 07-17-2002, 04:28 PM   #11
smooshy
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I'm hearing the same thing, but it's more regular. I usually can make it happen on hot days when I'm letting off the gas in 2nd or 3rd gear. When it's dropping from about 4k, in the range of 3k-2k I get that distinct pop. I wasn't too worried about it, but I'm glad to hear that it's fairly common and "normal".

However, I did get the programming adjustment done from the recall and it seems like the popping went away for about 1-2k miles, but it's back again (on hot days).

Just thought I'd chime in...

stan
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Old 07-17-2002, 04:35 PM   #12
Reciprocity
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Hmmmm....must start new thread.

NC
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