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taking off the catalytic converter #72370 Dec 22, 7:59pm Dec 22, 7:59pm
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taking off the catalytic converter
if i take off my cat.. and run a test pipe and straight pipe my exhaust.. will i loose or gain HP? i kno i will lose back pressure so my bottom end will suck but will my ECU throw a CEL and mess up my whole overall performance?


2000 GT-S - SOLD, 12/2003
1986 AE86 GT-S - STOLEN, unrecovered, 2/2004
1985 AE86 GT-S - built 4AGTE, SOLD 10/2009
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1994 GS300, 2JZGTE, HKS T04Z, 10/07-Current
Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72371 Dec 22, 8:34pm Dec 22, 8:34pm
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Dunno about performance gains or losses, but I doubt your car will pass emissions, so if you have to get that done, do it and then take it off.


Aqua Teen Hunger Force...number one in the hood, G
Re: taking off the catalytic converter [Re: slidr] #72372 Dec 22, 8:37pm Dec 22, 8:37pm
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And it's illegal... To much kaka will spread out from your exhaust pipe. wave


Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72373 Dec 22, 8:39pm Dec 22, 8:39pm
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yeah i know that but how about the CEL and will it perform like poop because of the CEL? i was going to get a pipe made from my header-back.


2000 GT-S - SOLD, 12/2003
1986 AE86 GT-S - STOLEN, unrecovered, 2/2004
1985 AE86 GT-S - built 4AGTE, SOLD 10/2009
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1994 GS300, 2JZGTE, HKS T04Z, 10/07-Current
Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72374 Dec 22, 8:42pm Dec 22, 8:42pm
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i Heard that you will gain some Hp if you take it off...But it's just what i heard... wink

Re: taking off the catalytic converter [Re: RoMkApOmKa] #72375 Dec 22, 9:04pm Dec 22, 9:04pm
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Originally Posted by RoMkApOmKa
i Heard that you will gain some Hp if you take it off...But it's just what i heard... wink
Yeah, and I think it weighs a few too, so it might be good for a weight reduction.


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Re: taking off the catalytic converter [Re: slidr] #72376 Dec 22, 9:08pm Dec 22, 9:08pm
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Originally Posted by slidr
Dunno about performance gains or losses, but I doubt your car will pass emissions, so if you have to get that done, do it and then take it off.


it won't pass emisions..thats the whole reason for having it on there.

Re: taking off the catalytic converter [Re: slidr] #72377 Dec 22, 9:09pm Dec 22, 9:09pm
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Originally Posted by slidr
Originally Posted by RoMkApOmKa
i Heard that you will gain some Hp if you take it off...But it's just what i heard... wink
Yeah, and I think it weighs a few too, so it might be good for a weight reduction.


you will gain...this is a big reason many japanese cars have to be "de-tuned" to come into america. emissions tests hinder performance.

Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72378 Dec 24, 7:58pm Dec 24, 7:58pm
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ok.. i know its illegal and it wont pass emission but i dont have to smog it anytime soon.. and im going to have it flanged so i can put it on whenever i want.. but the QUESTION that i have is.. will it throw the CEL and will it mess up my performance?


2000 GT-S - SOLD, 12/2003
1986 AE86 GT-S - STOLEN, unrecovered, 2/2004
1985 AE86 GT-S - built 4AGTE, SOLD 10/2009
2004 Camry LE, SOLD, 5/2007-10/2007
1994 GS300, 2JZGTE, HKS T04Z, 10/07-Current
Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72379 Dec 24, 7:59pm Dec 24, 7:59pm
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as long as you're o2 sensor stays in tact you should be fine.

Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72380 Dec 24, 9:14pm Dec 24, 9:14pm
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i don't know if you cel will come on...but it shouldnt mess up your performance. should help it, actually.

Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72381 Dec 24, 10:30pm Dec 24, 10:30pm
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no it wont but if you keep the cel on, and you get another engine problem, you'll never know because the light will already be on. You'll have to get your codes read.

Originally Posted by JDMCelicaGTS
ok.. i know its illegal and it wont pass emission but i dont have to smog it anytime soon.. and im going to have it flanged so i can put it on whenever i want.. but the QUESTION that i have is.. will it throw the CEL and will it mess up my performance?

Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72382 Dec 24, 10:34pm Dec 24, 10:34pm
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I passed emissions with my kazuma exhaust on...

they didn't even hook up my car to a machine, just stuck something into the ODBII port and let me go on my way. spineyes spineyes spineyes


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Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72383 Dec 24, 10:38pm Dec 24, 10:38pm
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I haven't done this but - Your cel should come on - the second O2 sensor is there just to see if the cat is working. You would see a performance gain only IF the ecu doesn't try to tune the engine to run cleaner (probably leaner) because it has no cat!
edit - there was a post on here or ecelica on how to trick the ecu into thinking there is a cat when there isn't - if you can do that I think you would definatly see a gain!

Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72384 Dec 24, 11:13pm Dec 24, 11:13pm
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I removed mine and the CEL came on but there havent been any noticable changes since it lit up. the increase is nice, I would rec. doing it. thumbsup


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Re: taking off the catalytic converter [Re: shabu] #72385 Dec 24, 11:32pm Dec 24, 11:32pm
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highly unlikely

Originally Posted by shabu
You would see a performance gain only IF the ecu doesn't try to tune the engine to run cleaner (probably leaner) because it has no cat!

Re: taking off the catalytic converter [Re: Steven] #72386 Dec 24, 11:55pm Dec 24, 11:55pm
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Originally Posted by Steven
highly unlikely

Originally Posted by shabu
You would see a performance gain only IF the ecu doesn't try to tune the engine to run cleaner (probably leaner) because it has no cat!
I agree. Shouldn't hurt your car at all. I wouldn't do it because I couldn't stand to see that cel on all the time. And I forget who said this before but yeah, if the cel light is already on and another problem arises, you wouldn't know about it. I say do it at your own risk.


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Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72387 Dec 25, 1:20am Dec 25, 1:20am
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wont the crap comin outta the exhaust turn ur bumper all black and nasty?


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Re: taking off the catalytic converter [Re: VVTi03] #72388 Dec 25, 4:31am Dec 25, 4:31am
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Originally Posted by VVTi03
wont the crap comin outta the exhaust turn ur bumper all black and nasty?

well.. i was planning on putting my stock exhaust but with a long tip a little that would stick out further than stock.. because when i had my N1 exhasut on, the tip came out further so it wont burn the bumper. I jsut want to try to get the most out of my stock muffler.


2000 GT-S - SOLD, 12/2003
1986 AE86 GT-S - STOLEN, unrecovered, 2/2004
1985 AE86 GT-S - built 4AGTE, SOLD 10/2009
2004 Camry LE, SOLD, 5/2007-10/2007
1994 GS300, 2JZGTE, HKS T04Z, 10/07-Current
Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72389 Dec 25, 6:08am Dec 25, 6:08am
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Originally Posted by JDMCelicaGTS
Originally Posted by VVTi03
wont the crap comin outta the exhaust turn ur bumper all black and nasty?

well.. i was planning on putting my stock exhaust but with a long tip a little that would stick out further than stock.. because when i had my N1 exhasut on, the tip came out further so it wont burn the bumper. I jsut want to try to get the most out of my stock muffler.


that should work, then. just hope the cel doesnt come on thumbsup

Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72390 Dec 25, 2:22pm Dec 25, 2:22pm
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the Check engine light will come on if you remove your cat off.

Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72391 Dec 25, 2:27pm Dec 25, 2:27pm
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y dont you just buy a racing cat?


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Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72392 Dec 25, 2:31pm Dec 25, 2:31pm
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the cel "IS" going to come on!the best thing to do is dont replace the fat pipe that go didrectly on the header(the one with the divider)start your custom pipe after this pipe(you can both flange the stock cat and your test pipe so you can switch back later for emisions) and put back the two o2 sensors.you can do a search and find out about the device that mimics a perfect o2 sensor for obd2 systems. or check splitsecond.com.about the gains,awsome!all rpm band but esp above 6k,(upwards of 15 hp with a straight through canister at the back)loud though! you ever bolt your stock muffler off?its louder than that but heavy loud and if your bends are good with one long length of pipe with no welds it should be free of most of that ringing sound.
ps: since you would be having the exhaust down it will be a good idea to wrap your exhaust with 2"x1/8th thick exhaust wrap.helps with scavenging and reduce the the sound of pipe vibrations.takes some pics and let us know what your butt dyno feels(if you cant get it dynoed)


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Re: taking off the catalytic converter [Re: JDMCelicaGTS] #72393 Dec 25, 7:27pm Dec 25, 7:27pm
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I guess "tune the engine to run cleaner" was the wrong way to put it but I thought the ecu would go into "limp home" mode if it didn't see any difference in O2 one and O2 two. I don't remember where I read that and I haven't actually done it, so you just might prove me wrong. In fact me and a lot of other people would be happy if you did! Post your results if you do it!

Re: taking off the catalytic converter [Re: shabu] #72394 Dec 25, 9:50pm Dec 25, 9:50pm
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it shouldnt make your car "limp home". as as already noted earlier by someone else...your ecu will turn out, and this is ordinarily fine but you won't know if there is another problem should one arise.

Re: taking off the catalytic converter [Re: RoMkApOmKa] #72395 Dec 26, 10:13am Dec 26, 10:13am
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Originally Posted by RoMkApOmKa
i Heard that you will gain some Hp if you take it off...But it's just what i heard... wink


Yepp...The gain shoud be 5-10 hp. But please, leave it on. There is allready enoug pollution.



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