removed my AIV, wierd problem, need opinions.

[240marcuSX]

ok, so i removed the AIV system thanks to poots teriffic write-up. and now i smell burning that i believe is coming from my dummy second cat, and it rattles when i rev to like 3500-4000 and let off. i have a couple options:

A) leave my stock exhaust on and put the AIV back on to stop this (because none of this happened before i removed the AIV)

B) leave the AIV off, and put my Greddy/Trust 3" exhaust on my naturally aspirated KA24E and look like a ricer for the next few months until i turbo.

just wondering what some opinions are, WHAT WOULD YOU DO!?

btw i have the TR EVO II and its HUGE, but i dont know how loud it will be, but i guess ill kiss my low end torque goodbye if i choose to put it on.

[coolcloo1019]

Hey man, what year is your car...mines a 90 and it does the same thing, its really annoying. I have the zigen fireball cat-back exhaust and but i have a test-pipe so i know its not that cat,but i dind't kno that there was another cat...is it closer to the engine? where is it located? Maybe I have the same problem as you.

[240marcuSX]

you smell burning too? your rattling is probably having to do with the exhaust rattling against another metal part. i think mine is inside the dummy cat, which is directly under your rear seats.

if you have a cat-back exhaust, you have already eliminated the dummy cat, and if you have the test pipe, you have no real cat either.

[[s3]]

It's probably the insides of your cat disintegrating...no biggie.

[Bbill528]

Hey i've looked for a ricer for about a year...3" won't do that much to your car, You might lose a little low end but really it's not that ricey....and you'll gain top end.

[Camel]

if you have a cat-back exhaust, you have already eliminated the dummy cat, and if you have the test pipe, you have no real cat either.

I believe that is is incorrect. The primary cat is in the downpipe from the exhaust manifold. And the secondary cat is a fake under the drivers seat. Unless you are in Canada, in which case it is a secondary cat. Nistech could tell you for sure. I can't remember what my s13 exhaust looked like. When I put on my cat back, the so called cat under the driver's seat was hollow which made me investigate this. When I put on my header, it is going to eliminate the primary cat in the downpipe but leave the hollow cat under the driver's seat. At that point, i am going to fit a catco high flow where the fake one is and keep the fake one for when i want to run without a cat (and get CELs).

[240marcuSX]

so wait, the dummy cat is the one directly under the driver seat??? ok, well if thats true, what i said is wrong, and the opposite is true, but either way, coolcloo has no cat on his car.

I guess ill strap on the greddy cat-back.

[Cyberkreig]

I would guess that the rattling is a heat shield problem. I wouldnt guess as to what the burning smell is.

Tho, I dont see how putting on a new exhaust will fix anything. It is a cat-back system, and will not eliminate the cat under the car. Also, if the system is new it too will 'burn in' for several days.

[EnzoRWD]

s13 has real cat under drivers seat. i dunno about s14's but they're different

[Altiman94]

the real cat is under the driver's seat. The "dummy" cat this guy is referring to sounds like an exhaust resonator from his description.

[240marcuSX]

its definately not the heat shield becuase mine fell off several months ago .

I am pretty sure that real cat is the one under the driver seat, but i was not positive, so i didnt want to argue it with camel.

and the cat-back that i have comes with a test pipe that you can either use, or not use. so i am pretty sure that by switching to the cat-back, it would solve both these problems, but so would putting the AIV back in and not look/sound silly for the next few months.

but anyway, i do not believe that the burning is coming from the primary cat, it seems to be coming from the (what i believe to be) dummy cat farther back on the exhaust system.

[180fan]

install the cat back. Solve the problem that's getting on your nerves and it'll be less work for you when you do indeed go turbo. If you find that your preference for having a quieter exhaust is greater than your ability to live with a l"ouder than what you would like" exhaust system, maybe you should have held off until you got the turbo then get the exhaust system.

ranting about the term "ricey" to start:

Honestly, people here are all afraid to do this and that because they're afraid of their car not being cool or afraid of being flamed here because of stuff being considered "ricey". I mean crap some people here think body kits are ricey, granted some are in bad taste, but to generalize like that is totally off the mark. Some think rims, new bulbs in their instrument cluster, pedals, etc are ricey. Honestly, who gives a $hit? It's not being done to your car so why give people a hard time if they think it's cool? People here really need to let off and let people do what they want to do to their cars if they want to. Think you can keep it from happening? No, you'd be a complete moron to think so. That look is "in" and people will buy it regardless of what you say or think and because people buy it businesses will continue to market it like that no mater how much you ***** and whine. Get over it.

[240marcuSX]

true 180fan, those are basically my thoughts, its not so much that i care what everyone thinks, but more that if im going loose alot of my low-end, and sound ridiculous, since i dont really NEED the extra flow (no turbo), then the cons outweigh the pros.

well i bought the exhaust system early because it was for an amazing price, and i couldnt pass it up.

so no one knows what the burning might be? besides the inside of my cat disintegrating?

[rco8786]

if a big exhaust takes away your low end torque at all, you won't notice it...but i've heard that this is just a rumor anyway...and since you'll still have a cat, you'll still have a decent amount of backpressure if ur that worried about it.

[Camel]

the real cat is under the driver's seat. The "dummy" cat this guy is referring to sounds like an exhaust resonator from his description.

Like i said, I am not so sure about the s13, but i can tell you authoritatively that the cat on an s14 is in the downpipe from the exhaust manifold. What looks like a cat under the drivers seat is actually a straight pipe in the us (2nd cat in canada). The resonator is part of the piping (welded in) to the muffler.

Someone with a s13 FSM step in and set us all straight with a diagram please.......Oh sh*t I have both. Let me post the images here. Guess the s13 doesn't have the cat in the downpipe like the s14 does. Oh well, hope the diagram helps anyway.





And I did actually lose a good bit of low end with a large exhaust on an NA setup. But when I put the silencer in, most of that came back. It seems to have just shifted the powerband a little further north on the tach. Just my experience though.

[Camel]

but anyway, i do not believe that the burning is coming from the primary cat, it seems to be coming from the (what i believe to be) dummy cat farther back on the exhaust system.

If the dummy cat you speak of is welded in, that is your resonator. Mine rusted out on my 91, so i had it straight piped for 25 bucks. No real change in exhaust sound. I never had a burning smell though...

[sideshow]

now this might be a weird question but how did u plug it up if you even did? because im assuming you took off the lil black box and the tube that comes off the downpipe, so how did u plug it and if u used sealer maybe thats whats burning

[240marcuSX]

sideshow - you mean what did i use to plug the hoses from the AIV? I used spare tuner lugs, and put a hose clamp on and tightened, because they were a perfect fit, and im crafty, until i can get some kind of real plug and sealer.

but the burning is definately coming from the rear.

[Blue Blunder]

Did the removal of the AIV fix any of the eratic idle problems or provide any other benefits. Also by plugging the tube your forcing the rerouted exhaust air that should pass through the valve to be sent back into the system so thats probably causing either the tube to become overheated.

[240marcuSX]

ive noticed that it idles a little higher, and the rattling, and burning smell. I mainly got rid of mine because i needed space for the Turbo.

yeah, eventually im gonna saw the metal tube off and plug it at the manifold or not even worry about it, a turbo mani will be on soon enough.

[skydragoness]

Hmm. I left my AIV on. I just disconnected it from my intake, put a 3/4 tube on it, and put a breather filter on the end of it. Then, I bought a new cat, 300zx fuel filter, 02 sensor, changed plugs/wires/distributor cap. And my hesitation/stumbling issues cleared themselves up. The idle is pretty much dead-on 750 or so, but it sure doesn't dip to 300rpm anymore. And the car pulls like hell. A bit of fluctuation is normal i think when making sudden stops as there's some flow changes. I think. I think having the tach in the center on my gauge cluster( i have HUD) makes the fluctuations all the more noticeable.