Catylitic Convertors... My car has 4... I want them GONE. Can it be done?

[longhornsqx4]

I really didnt know where to post this, but I figured there are alot of people that could help me here.

Anywho, I drive a 01 Infiniti Qx4. VQ35De engine, 2wd. It has 4 cats, and 4 02 sensors.

I built an exhaust 2-3 years ago, and it need to be redone as its rusting pretty bad. What I would like to do is completely remove everything after the factory headers. As Im sure the cats are a HUGE restriction. What I dont understand though, is how it will cause the car to run. As it goes:

Header -> 02 -> cat -> 02 -> cat (X2 as this is on each side)

From my understanding, the rear 02's dont do anything, but I would have still have to weld bungs for them. But I dont get if I simply put both 02 sensors after the header, would the car still run right? Would it adjust properly?

Im hoping there are some people here with some experience that could help me it. Ive never done a full exhaust like this, and I dont know if my fluxcore welder is upto the task lol, I dont want it cracking and failing in a short ammount of time. Is there a cheap place to find the cat flanges / 02 bungs?

Thanks for any help appreciate it

[IanS]

Catalytic converters are not really that restrictive, and they keep the emissions down.

If you really want to do something, ditch the secondary cats, they are only there to try and clean up whats left by the primaries.

Trust me, removing all the cats will net you almost no performance gain, and you will have a CEL to deal with.

[Jesda]

Don't tell the federal government.

[longhornsqx4]

Its guaranteed to throw a CEL if you ditch all of the cats?

Would I still pass emissions if I removed the secondaries?

I was going to remove all 4 and then just pay a guy the extra coin for the fake e-test, but if replacing only 2 would give me the same gain...... then I might do it...

But Im sure the primary cats are still a good restriction...

[snwbrdr435]

Besides you wanting a less restrictive exhaust any other reasons?

Not to mention the fact its illegal to remove working cats.

[IanS]

Its guaranteed to throw a CEL if you ditch all of the cats?

Would I still pass emissions if I removed the secondaries?

I was going to remove all 4 and then just pay a guy the extra coin for the fake e-test, but if replacing only 2 would give me the same gain...... then I might do it...

But Im sure the primary cats are still a good restriction...

Yes, you will have a CEL.

You may be able to pass the sniffer without the secondaries. With a little tweaking, and an engine in top shape, you should be able to make it pass. That being said, if there is a visual inspection, you will fail.

Cats are not nearly the restriction people make them out to be. There are many more effective ways of making power, especially when working on a truck engine. You are neither running high revs, nor a turbocharger, so a little restriction isn't the end of the world.

You want more power? Open your intake, reduce parasitic loss, and start thinking about forced induction.

Also remember, this is a truck, so you should be trying to make more usable torque, instead of top end power.

[W O T]

4 cats???

[Murdered_T]

The first two pipes after the headers are not Cats. They are resonators, they look like cats but they are not. They fail, ALOT.

pn=20200-5w51020100-5w510

Don't worry about removing the CAT's they power difference is unmeasurable on the trucks.

[longhornsqx4]

Are you sure? How can you tell if they have "failed"

I coulda swore Ive read in multiple threads that I have 4 cats.... but they may have been mistaken....

Anyone chime in please?

[Murdered_T]

<----Worked for Nissan for 10 years.

They fail because they rust through and they are noisy, Nissan used to make a repair kit for them, some old timers in the parts places might know what you are talking about if you ask them about it cause they run about 700 @ the dealership. You can get rid of those and there wont be a difference. Jeggs makes an 02 eliminator that screws into the bunghole and take the sensor out of the direct stream of the exhaust. If you are REALLY admit on removing them.

[longhornsqx4]

I think youre incorrect and I do have 4 convertors

http://www.trademotion.com/par...gid=2

It says convertor upper right, convetor right, convertor upper left, convertor left........

Pretty sure i have 4

[Murdered_T]

PLEASE LOOK AT THAT ILLUSTRATION CLOSER.

Number 5 is a heatshield. NOT A CONVERTER.

[longhornsqx4]

Nevermind Im stupid, the lower ones are just covers arent they.....

Ok, change of question then, so there is an 02 before the cat, and then an 02 after. If i put a test pipe inplace of the cat, would I get a CEL? and would that CEL affect performance?

THen when emmissions/ car sale timec ame around, I could just put the cat back in..... and the car would run fine and emmissions freindly again?

Just need some help on what the car will run like etc with it removed.

[longhornsqx4]

Thanks for your help btw, appreciate it alot

[Murdered_T]

Nevermind Im stupid, the lower ones are just covers arent they.....

Ok, change of question then, so there is an 02 before the cat, and then an 02 after. If i put a test pipe inplace of the cat, would I get a CEL? and would that CEL affect performance?

THen when emmissions/ car sale timec ame around, I could just put the cat back in..... and the car would run fine and emmissions freindly again?

Just need some help on what the car will run like etc with it removed.

Yes the first 02 sensor is to measure the emissions directly out of the engine, where the second measures if the CAT is doing its job. You leave the first sensor in the bunghole and remove the second sensor out of the direct path of the fumes. (the bung) the part can be made yourself or you can pick one up for like 7 bucks.

[Murdered_T]

Thanks for your help btw, appreciate it alot

NP man anytime.

[Murdered_T]

Check this out, it should help a little finding the CAT eliminators.

It SHOULD, all I didwas skim through it.

http://www.topix.com/forum/aut...BF/p7

[longhornsqx4]

Oh so to remove the cat, you need to trick the second 02 into thinking its still there, then I wont get any CEL's.

So if I do decide to remove the cat, and put in a test pipe and reset my ecu so it learns the new tune, then e-test time comes around (late september), can i put the cat back in place, say a week before, and the car will pass e-test again and the car will be working perfectly>?

Im used to carbs, where there is no electronics obviously lol, so I dont get how these ECU's control or function emmissions wise

[Murdered_T]

NO the ECU wont reset. You need that bung spacer.

[RCA]

OMG doing exhaust work on a car with 4 cats must be the closest thing to hell on earth...

[longhornsqx4]

NO the ECU wont reset. You need that bung spacer.

Well I meant i have my battery negtive pulled for ong periods of time all the time for my stereo work, so I thought the ecu would reset itself and learnt he new "curves"

I havent looked into the 02 eliminater, but its just a spacer that pulls it up and out of the airflow?

Ill have to read that link, Im gonna measure the cats tomorrow and probly pick up some exact length test pipes

[longhornsqx4]

Oh damn, nevermind, after reading that thread you posted, the Catalytic convertors, are attached right to the exhaust manifold??? then a short piece of pipe, then the resonator ( would explain why the second part was so much smaller)

If the second piece is a resonator, I will eliminate it, if the cats are tucked way up in the engine connected to the exhaust manifold I wont worry

SO what comes first, after the exhaust manifold, cat, or resonator

[Murdered_T]

Manifold,cats, resonators, y pip with attached main muffler, secondary muffler.

the cats are the small soda can looking things with 7 bolts upstream and 3 downstream.

[longhornsqx4]

Well that sucks, I guess I will just be removing the resonators and making an exhaust from the bottom of the cat and on back