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clogged cats question

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Old 04-12-2014, 12:28 PM   #1  
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I took my car to a exhuast shop to check my cats .all he did was go behind the car and told me to rev it and said 1 or all my cats are clogged.

I never had a check engine light for cats but im losing a lot of power. Im gonna get a warpspeed y pipe and gut the other precat. They won't do it I gotta find someone else to do it. If it happens to be my catalytic converter should I stay stock or high flow. My biggest concern is my car sounding like a civic. Right now its more of a consistent roar. I dont want that raspy in and out sound. I also don't wanna loose low end cause I usually dont shift gears past 3k. Right now I have a single tip Megan catback .

Heres an idea of what my exhaust setup is.the first couple pics were removed

http://s1275.photobucket.com/user/si...bile%20Uploads

Last edited by NmexMAX; 04-14-2014 at 07:47 AM.
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Old 04-12-2014, 01:56 PM   #2  
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You need to replace all of that stuff you got going on there.the main cat isn't going to cause that much drone all that comes from the undersized muffler and resonator.as far as precats just take off gut and get sims or anti foulers.

Btw searching helps alot on this site!
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Old 04-12-2014, 04:30 PM   #3  
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On the warpspeed website it shows a picture of the 02 ypipe and it says no precats removed.
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Old 04-12-2014, 05:46 PM   #4  
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On the warpspeed website it shows a picture of the 02 ypipe and it says no precats removed.
It connects to the oe pre cats just gut your cats get some sims,anti foulers or o2 relocates and a new main cat from warp,cattman or magnaflow universal unit the replace your catback with something decent and be done
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Old 04-12-2014, 10:22 PM   #5  
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It connects to the oe pre cats just gut your cats get some sims,anti foulers or o2 relocates and a new main cat from warp,cattman or magnaflow universal unit the replace your catback with something decent and be done
Idk wtf ur saying. Ur making no sense. Does the warpspeed y pipe eliminate one precat? One of my cats are clogged. I figured il get a ypipe to eliminate one precat and gut the other precat. And take it from there. If the main cat happens to be clogged il replace it. Im not asking about a full exhaust system.

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^
A y-pipe can't replace a precat

You need headers or something that looks like on the LEFT and RIGHT side
I don't understand y I get different answers .ive been told the stock y pipe on the 02 max has a pre cat on it and the other bank precat is on the headers. So your telling me on the 02 maxima. If I wanna eliminate both precats I either need to gutem both or get headers? If I get a y pipe it won't have anything at all to do with the precats?

Last edited by NmexMAX; 04-15-2014 at 07:53 AM.
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Old 04-13-2014, 05:28 AM   #6  
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I don't understand y I get different answers .ive been told the stock y pipe on the 02 max has a pre cat on it and the other bank precat is on the headers. So your telling me on the 02 maxima. If I wanna eliminate both precats I either need to gutem both or get headers? If I get a y pipe it won't have anything at all to do with the precats?
02/03 have pre cats bolted to exhaust manifolds.
Warpspeed Y pipe bolts to the factory cats.
Remove factory cats gut them.
Bolt on Y pipe
3.0 engines have cats in the Y pipe

RESEARCH.
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Old 04-13-2014, 10:45 AM   #7  
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02/03 has one pre cat in the y-pipe and one pre-cat bolted to the left bank exhaust manifold.
Warpspeed Y pipe eliminated right bank pre-cat and bolts to the left bank pre-cat.
Remove left bank pre-cat and gut it.
Bolt on Y pipe.
None California emissions engines had both pre-cats in the Y pipe.

RESEARCH.



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^
A y-pipe can't replace a precat

(snipped)
It has been said many times before - George, you're a moron.

Last edited by NmexMAX; 04-14-2014 at 07:46 AM.
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Old 04-13-2014, 03:49 PM   #8  
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Thinking more and more about a ypipe these days but getting conficting answers from this thread. I have an 03. My understanding from reading and looking at the warpspeed image on their site is that the 02-03 3.5L warpspeed ypipe DOES NOT eliminate any precats. It bolts on to them. Can someone who has this ypipe for these model years confirm?
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Old 04-13-2014, 05:08 PM   #9  
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02/03 has one pre cat in the y-pipe and one pre-cat bolted to the left bank exhaust manifold. Warpspeed Y pipe eliminated right bank pre-cat and bolts to the left bank pre-cat. Remove left bank pre-cat and gut it. Bolt on Y pipe. None California emissions engines had both pre-cats in the Y pipe. RESEARCH.
Dennis the 03 precats arnt part of the Y pipe brother.i know alot of confusion but both precats are separate units from the Y pipe and the front is ceramic substrate and the rear one has a metallic core pita to remove without Hammer and HD screwdriver.

And yes george is a pot smoking idiot!
http://www.courtesyparts.com/maxima-...1981_1983.html

I have the warpspeed Y pipe 2.5" SS unit only was o2 bung locations.think dallas fixed that issue sence then.they bolt directly to the precats and to clear things up goto rock auto select 02/03 maxima the goto converter tab it will show you how each one looks

Last edited by NmexMAX; 04-14-2014 at 07:46 AM.
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Old 04-13-2014, 05:55 PM   #10  
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I have the warpspeed Y pipe 2.5" SS unit only was o2 bung locations.think dallas fixed that issue sence then.they bolt directly to the precats and to clear things up goto rock auto select 02/03 maxima the goto converter tab it will show you how each one looks
Why get a warpspeed!?
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Old 04-13-2014, 06:05 PM   #11  
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Why get a warpspeed!?
STFU george im helping someone here who can actually drive his car.
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Old 04-13-2014, 06:54 PM   #12  
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STFU george im helping someone here who can actually drive his car.
Cheapo
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Old 04-13-2014, 07:36 PM   #13  
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Cheapo
Cheap lmfao I have 2nd gen and 3rd en cattman headers and 2.5&3" cattman exhaust.i have more real parts for my car then yours is worth so stop being an azz.and ive been in the maxima game sense 97 so check yourself

Last edited by The_Fixer; 04-13-2014 at 07:45 PM.
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Old 04-13-2014, 07:39 PM   #14  
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Cheap lmfao

I have 2nd gen and 3rd en cattman headers and 2.5&3" cattman exhaust
Those aren't that much.......
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Old 04-13-2014, 08:40 PM   #15  
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Originally Posted by The_Fixer View Post
I have the warpspeed Y pipe 2.5" SS unit only was o2 bung locations.think dallas fixed that issue sence then.they bolt directly to the precats and to clear things up goto rock auto select 02/03 maxima the goto converter tab it will show you how each one looks
Thanks. That's what I thought.
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Old 04-14-2014, 03:22 PM   #16  
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Same problem, but worse on mine. Tripped P0300 misfire code. BOTH precats are separate from the Y-Pipe. If you want to replace ANY of the precats, you must get headers or gut both of them. The exhaust system on both banks is: Manifold, Precat, Y-Pipe.

My car is a 2002 6-Speed.

-Nathan
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Old 04-14-2014, 03:30 PM   #17  
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Old 04-14-2014, 03:42 PM   #18  
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Same problem, but worse on mine. Tripped P0300 misfire code. BOTH precats are separate from the Y-Pipe. If you want to replace ANY of the precats, you must get headers or gut both of them. The exhaust system on both banks is: Manifold, Precat, Y-Pipe.

My car is a 2002 6-Speed.

-Nathan
THe_Fixer says this is wrong...
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Old 04-14-2014, 04:23 PM   #19  
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What are you talking about George? He has already clarified that both precats are separate from the Ypipe. Why are you trying to confuse an issue that has already been resolved?
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Old 04-14-2014, 05:17 PM   #20  
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Same problem, but worse on mine. Tripped P0300 misfire code. BOTH precats are separate from the Y-Pipe. If you want to replace ANY of the precats, you must get headers or gut both of them. The exhaust system on both banks is: Manifold, Precat, Y-Pipe.

My car is a 2002 6-Speed.

-Nathan
I have the same issue, having trouble figuring out what to do as well. Searching gets me a lot of info of fixing this problem quickly and easily with a ypipe on a 00-01, but nothing to help me figure out what to do with this 2002 I have now.
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Old 04-14-2014, 05:45 PM   #21  
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Cheap lmfao I have 2nd gen and 3rd en cattman headers and 2.5&3" cattman exhaust.i have more real parts for my car then yours is worth so stop being an azz.and ive been in the maxima game sense 97 so check yourself
damn.. game..
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Old 04-14-2014, 06:16 PM   #22  
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I have the same issue, having trouble figuring out what to do as well. Searching gets me a lot of info of fixing this problem quickly and easily with a ypipe on a 00-01, but nothing to help me figure out what to do with this 2002 I have now.
The info i posted is 100% i have been thru it, fixed it, modded it and kept going and i have no problems. You guys are getting 5th gen and 5.5 gen mixed up thats where the issue is! 3.0 engine vs. 3.5 engine same body different under the hood.
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Old 04-14-2014, 06:23 PM   #23  
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Exactly what thefixer said, I have an 02, both cats are separate from the y-pipe, gutted and work great.

Use a spacer for the O2 sensor, and you won't get a code for it. Also, no chance of cat material getting back into cylinder, to "damage" the rings.
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Old 04-14-2014, 11:54 PM   #24  
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Exactly what thefixer said, I have an 02, both cats are separate from the y-pipe, gutted and work great.

Use a spacer for the O2 sensor, and you won't get a code for it. Also, no chance of cat material getting back into cylinder, to "damage" the rings.
What kind of spacer did you use? What do you mean by no chance of cat material getting back in the cylinder?
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Old 04-15-2014, 02:00 AM   #25  
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A spacer is like a short piece of pipe that will screw into the exhaust pipe's O2 hole and allow you to screw the O2 sensor into it.

Click here to see bigger photo

A problem that can happen is that the catalytic material in the pre-cats can break up into a fine powder. This powder can get sucked back into the combustion chambers via the EGR system. It also goes into the main cat and plugs the cat up.

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You guys are getting 5th gen and 5.5 gen mixed up thats where the issue is!
Count me as one of them.

Last edited by NmexMAX; 04-15-2014 at 07:52 AM.
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Old 04-15-2014, 02:56 AM   #26  
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I have the same issue, having trouble figuring out what to do as well. Searching gets me a lot of info of fixing this problem quickly and easily with a ypipe on a 00-01, but nothing to help me figure out what to do with this 2002 I have now.
Feel free to PM me about it. I spent a LOT of time and money diagnosing and figuring out the problem. I would be more than happy to run through everything I've done and all the proper testing methods to help save you some headache and money. It's quite an elusive problem in a lot of cases.
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Old 04-15-2014, 04:57 AM   #27  
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A spacer is like a short piece of pipe that will screw into the exhaust pipe's O2 hole and allow you to screw the O2 sensor into it.

Video Link: http://www.ebay.com/itm/O2-oxygen-sensor-test-pipe-extension-extender-spacer-M18-X-1-5-2-/161119594890?pt=Race_Car_Parts&hash=item258379e98a &vxp=mtr

A problem that can happen is that the catalytic material in the pre-cats can break up into a fine powder. This powder can get sucked back into the combustion chambers via the EGR system. It also goes into the main cat and plugs the cat up.
So is this used for the aftermarket pipe or should it be used anytime u gut precats?
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Old 04-15-2014, 05:02 AM   #28  
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^
You drill one of them out and use the other as a extension like this

then it goes o2 sensor -> foulers -> pipe


http://www.b15u.com/threads/4124-Ins...nsor-Spacer%29

Last edited by george__; 04-15-2014 at 05:09 AM.
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Old 04-15-2014, 05:08 AM   #29  
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So is this used for the aftermarket pipe or should it be used anytime u gut precats?
These work better and are more professional and less work.

http://vibrantperformance.com/catalo...sort=2a&page=2
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Old 04-15-2014, 05:10 AM   #30  
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^
Those are the anti-foulers... You can get them at part stores locally probably. You drill one of them out and use the other as a extension like this

then it goes o2 sensor -> foulers -> pipe

http://www.b15u.com/threads/4124-Ins...nsor-Spacer%29
I got that part. But do they just go on the aftermarket y pipe? Say I just wanna gut precats and dont get a aftermarket y pipe. Do I put those on all the sensors? just the precat sensors?
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Old 04-15-2014, 05:10 AM   #31  
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Btw if you know whats good for you stay Away from george advise.you dont have to take my advise on it just search his threads.
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Old 04-15-2014, 05:20 AM   #32  
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Btw if you know whats good for you stay Away from The_Fixer's advise.
He's actually the breaker
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Old 04-15-2014, 05:58 AM   #33  
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I got that part. But do they just go on the aftermarket y pipe? Say I just wanna gut precats and dont get a aftermarket y pipe. Do I put those on all the sensors? just the precat sensors?
Yes. That's how I have it on my 02 Max. gutted precats and nonfoulers (what they are called) are installed on both secondary o2 sensors while attached to factory y pipe. the car is happy and doesn't throw any codes.

If you run a megan catback, your drone will increase so you may need to make some kind of change to the catback eventually if its too much for you.

I installed stainless steel nonfoulers on mine. Cost a bit more, but I think it would be easier to remove if I need to.

http://www.bigdaddiesgarage.com/straight-cel-fix.html
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Old 04-15-2014, 06:33 AM   #34  
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For those that have done it....separating those precats from the manifolds must be nasty work. Heat would be the key I would imagine. Any thoughts/tips?
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Old 04-15-2014, 07:09 AM   #35  
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For those that have done it....separating those precats from the manifolds must be nasty work. Heat would be the key I would imagine. Any thoughts/tips?
Yeah buy hardware in advance and cutoff wheels!its better to cut the heads off and replace the bolts with new after you have the unit out where you can work on it better.

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I got that part. But do they just go on the aftermarket y pipe? Say I just wanna gut precats and dont get a aftermarket y pipe. Do I put those on all the sensors? just the precat sensors?
gut precat install antifoulers back in oe places call it a day!its not complicated at all you will not need one at the main cat.

Last edited by NmexMAX; 04-15-2014 at 07:52 AM.
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Old 04-15-2014, 10:00 AM   #36  
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^^This

Plus the part about not listening to George, if you want good advice that is.
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Old 04-15-2014, 03:08 PM   #37  
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OK, my apologies for not being completely clear on my last post.

VQ30DE (95-01) - Fed Spec cars have one precat built into the Y-Pipe. Somebody please confirm that it is the rear bank (Bank 1). Cali spec cars have separate precats on both banks.
VQ35DE (02-03) - All specs have precats separate from the Y-Pipe.

If you have a 2002 or newer Maxima then your precats are separate pieces in the exhaust system and must be removed either by installing headers or gutting them separately. Purchasing a Y-Pipe as a means to replace them will leave you wishing you had listened to the information given on this site...

...except information given by george, who seems to be the most discredited member I've ever seen on this site. Lol.
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Old 04-15-2014, 03:13 PM   #38  
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ok, my apologies for not being completely clear on my last post. Vq30de (95-01) - fed spec cars have one precat built into the y-pipe. Somebody please confirm that it is the rear bank (bank 1). Cali spec cars have separate precats on both banks. Vq35de (02-03) - all specs have precats separate from the y-pipe. If you have a 2002 or newer maxima then your precats are separate pieces in the exhaust system and must be removed either by installing headers or gutting them separately. Purchasing a y-pipe as a means to replace them will leave you wishing you had listened to the information given on this site... ...except information given by george, who seems to be the most discredited member i've ever seen on this site. Lol.
i support this public service message!
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Old 04-15-2014, 04:22 PM   #39  
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I been in traffic all day and im afraid of what my cars gonna sound like after gutting cats. Some of these civics sound horrible. I saw a beamer screaming like its wide open and the car looked like it wasn't moving. Please guys lets get some sound clips with ur setup. There's a few on YouTube but they don't list mods.



Now that sounds perfect. Souns like mine but a little louder. I have megan cat back but its the only one ive seen with a single tip. I don't know what difference to expect gutting cats and adding a y pipe.

Last edited by maximasicilian123; 04-15-2014 at 04:35 PM.
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Old 04-15-2014, 04:37 PM   #40  
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I been in traffic all day and im afraid of what my cars gonna sound like after gutting cats. Some of these civics sound horrible. I saw a beamer screaming like its wide open and the car looked like it wasn't moving. Please guys lets get some sound clips with ur setup. There's a few on YouTube but they don't list mods.
A magnaflow 12640 will quiet it right down
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