SpdElemts

I failed smog again today and i suspect it is my cat. I am going to buy a new one and I was wondering would a high flow cat change emissions compared to an OEM one?

AlligatorBling

use stock cat for test, then go testpipe.... i dont think your cat would be the cause, but then again i live in va where i pass inspection with no cat because i bought the tires from the guy.

90RS13

"high flow" cats are just as good as oem as far as emissions goes. Sometimes even better.

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XxJaPxOxNeEs23xX

what brands of high flow cats would you recommend using.

kazuo

Most aftermarket high flow cats (like the CATCO) isn't 3-way cat, which is what OEM Nissan cats are. Most of the high flows are 2 way.

And that's bad, cus it won't reduce NOx... sure a cat doesn't do that much when it comes to NOx, but every little bit helps...

SpdElemts

Yea my Nox Is high. The guy at the smog shop checked my EGR crap and he said its all in working order. Then he said it is probally my cat. My Nox Numbers were: 15mph max-704 meas-1502 25mph max-738 Meas-1786. Would a messed up cat cause that high Nox?

Yoshi

how old is your cat?
they don't last all that long, and if you have a s13 with the factory cat, chances are pretty good that it's shot.

I've gone thru 2 s13s so far, and both have had used up cats

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Ritz S14

My friend has a modified supercharged mr2. With a stock cat, he'd fail. With a high flow fat, he failed even worse.

Let me know if you need a smog and located near Hayward, I'll hook you up price wise.

SpdElemts

I just bought the car so i dont know how old the cat is. The car does have 157k miles tho. But when i went under the car it looks brand new. But of course thats just looks. Is there a way i can tell that my cat is bad? BTW what if it isnt the Cat or EGR what else would cause high nox?

THanks

SpdElemts

Aite i took out the cat today and inspected the honeycomb and it looks like its brand new...But i just put the new one in anyways. How do i know the old one is bad? What else can be the problem other then the Cat and Egr?

Pacman

I have a question. When I went to Kragen they sold universal ones for like $55 and stock for $100. Are the universal ones 3-way?

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Ritz S14

They stopped using 2 way cats in the late 70s/early 80s.

PinkPanther

Are you DAFT son? do you realize they are high flow because they allow more untreated exaust to pass through the unit? On top of that, aftermarket cats have a fraction of the life of an OEM cat. Have you ever looked up the price of an OEM cat? I've had to replace cats on people's cars that approached four digits in price. don't post on tech questions if you don't know what you're talking about.

SpdElemts

Well I went to go smog it today with the new cat. Didn’t pass... It actually did a lot worse then before. What’s funny is that I swapped the Old one out with the exact same one. The smog guy said that the brand of the cat I am using is not good, Its a CarSound or SoundCar either one. I am really out of ideas. Please help. I’m really stressed out about this; I want to get this thing registered already. I am almost to the point of selling this car.

Thanks

nightwalker

typical thing to do when faced with a problem is to throw parts at it and hope. Take it to someone who knows diagnostics and they'll find your problem for you. If you're not too far from El Cerrito, you can visit my brother at Quality Tune-Up on SanPablo. It's next to a Nation's burger and burger king. He's a great driveablility guy. That way you can zero out your problem and just fix what's wrong without replacing a bunch of stuff.

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PinkPanther

My recommendation for the cat: go out and buy a catco direct-bolt-on replacement OEM cat. This will TEMPORARILY solve a defective cat problem, if the cat was the source of your failure. You said you received a failure for NOx; EGR is most likely at fault for this. NEVER trust the people at emissions test facilities! (unless you bribe them) They hate you, your children, your children's children, and so on...

kazuo

CATCO is 2way, OEM is 3way.

Do NOT get a CATCO if you're trying to pass smog. :P

RandomTech is the only aftermarket high flow I know of thats 3-way and comes with flanges for our cars.. I'm sure you can get any 3-way and get flanges welded on. ;p

AllenRPS13

high flow cat do not help u to pass smog and just even worse, the one from random technology is guaranteed to pass smog, may be u try that one, my friend also using it now

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S14DB

With your nox going up fast like that I say your EGR is stuck.

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SpdElemts

All of my vacuum lines for the egr are getting a good amount of vacuum while revving the engine and the egr solenoid has been tested and it works. What would cause the the egr to be stuck?

S14DB

How was the EGR valve tested? Was the asembly taken off the car and inspected to open and close fully? If your cat was bad I would expect you to fail across the board not just on NOX. The rasing rate is a sign of the valve being stuck.

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meatish

There is a reason that OEM cats cost so much; they work great. Stick with them, and tune your car up as well, if you havent already. Plugs/filters etc..

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SpdElemts

Yes, Everything EGR related was tookin off the car and tested and it all worked flawlessly.

SpdElemts

I was just wondering would having a after market exhaust cause me to fail? My friend with the same exact car has the same symptoms with the EGr but he passed, he also has stock exhaust. BTW i have a apex gt spec exhaust.

thanks

90RS13

Sorry, I was just talking from the experiances I've had. I've known people that had modified turbo engines, failed emissions, got a high flow cat, and then passed. I guess their stock cat's were just that bad though.

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SpdElemts

Can someone answer my question?

Thanks

zeek

theres a thing called a dump pipe just use that , or you could rig up a vaccum diverter to lower you nox numbers..