kiling my cat.......meow....

[theizzardking]

so i've decided i'm want to cut my cat out, is there any issues i need to worry about? will it mess with my sensor readings anything special i need to do?

i live out in the country no emissions,inspections, nothing... and want to squeeze everything i can out of my fuel and engine, so why not eh?

i know the theory behind it, but does anyone have an idea of real world gains? between that and a new fuel filter and a few other minor tweaks i'm hoping to bump my mpg's by a couple of miles, i may not do this if it's more work then what i gain .....thoughts?

 

[Elton H]

gains will be very little if any id just leave it alone

 

[Baja Runner]

Gains are keeping it in and helping us breathe easier. :flipoff:

 

[Mudtallica]

I tried it & had all kinds of issues with the O2's.. Finally broke down & replaced the whole exhaust with 2 new cats.. O2 issue's have stopped..

 

[Brutus]

Gains are keeping it in and helping us breathe easier. :flipoff:

Me too. I've been puttin it off till after deer season and Thanksgiving. I'm prolly gonna do it very soon.
With over 250k on it, I'm hopin it helps somewhere.

 

[bikerjosh]

I would think removing it may cause problems with the downstream o2 sensor. Interested to see what will happen after 5-10k miles.
Josh:snacker:

 

[TheDurk]

Well, you WILL get a MIL aka CEL with a P0420 code. You can ignore that, but you won't know when another, possibly serious, problem comes up.

Beyond that, the reduced back pressure may be an issue. I doubt you would gain much in mpg and the truck would become difficult to sell with a permanent MIL on. Putting it back could be expensive, depending on whether you can reuse the original cat.

 

[awdjunkies]

Yeah, you get better gains when you are S/C or T/C.

 

[BTO]

so i've decided i'm want to cut my cat out, is there any issues i need to worry about? will it mess with my sensor readings anything special i need to do?

I did this when I was a kid. Probably the worst thing I ever did to a car. I know better now. The thing never ran right after that "modification" that I thought would help it breath.

Engines are designed and calibrated to work with the cat. If you remove the cat the engine will set the cel and go into open loop mode, killing the efficiency.

I'd say if you are not happy with the performance of your 4R then sell it and get something with more power like say a 4th gen with a V8 in it.

 

[FSRMaster]

dont do it. absolutley no power gains, will screw up your downstream o2 sensor, and when you bring the car to a stop and let it idle with the fan on, even on the minimum setting, the gasses will seep into the cabin and you will hate yourself for taking your cat out. You wont be able to open any of the passenger side windows, or your rear window, for the same reason.

if you DO take your cat out though, pm me. I had mine stolen and would LOVE to take yours off your hands.

 

[the great him]

izz if you want to do something to help it, get a bigger diameter cat and put it in, it will be less restrictive and still work as it should.

 

[awdjunkies]

Like a HFC correct?

 

[steezemcqueen]

I gutted mine about 2 months ago. I had a noticeable gain in power and about 2 MPG increase.

I am supercharged though.

 

[ChildrenOfBodom]

CEL's...

None of you people have heard of an O2 Simulator? I've read about them a hundred times on here at least.

I have a year old high flow 2.5" cat... they're legal and typically provide about the same power gains.

Dylan, you have an O2 sim?

 

[steezemcqueen]

Dylan, you have an O2 sim?

Not yet. No CEL yet. I will get one if it ever comes on.

 

[DC runner]

I want to thank all the level headed members on here. You are, of course, free to do what you want; but the majority opinion is that it is a horrid idea. You will see, at best, a minimal gain and you will increase your exhaust. We started putting Cat's on cars for a reason. You may not be aware, but without a cat, you are throwing out incredibly nasty fumes that have been shown in some pretty serious studies to cause all manner of issues. Hence why we have Cat's, which use some neato science to reduce the exhaust coming out.


If obscure "save the world" comments don't affect you, then how about this. I travel to WA to visit family often, so this is a personal pea. SAVE MY AIR.

 

[steezemcqueen]

I want to thank all the level headed members on here. You are, of course, free to do what you want; but the majority opinion is that it is a horrid idea. You will see, at best, a minimal gain and you will increase your exhaust. We started putting Cat's on cars for a reason. You may not be aware, but without a cat, you are throwing out incredibly nasty fumes that have been shown in some pretty serious studies to cause all manner of issues. Hence why we have Cat's, which use some neato science to reduce the exhaust coming out.


If obscure "save the world" comments don't affect you, then how about this. I travel to WA to visit family often, so this is a personal pea. SAVE MY AIR.

Did you not see where i said i saw a noticeable gain in power and a MPG increase?

I bet you i am still polluting less than a hummer

 

[Clownmeat]

Gutted mine, turbo spools faster, more power, more mpg, no codes. My wifes 4runner on the other hand I left the cat and just put a flowmaster on it.

 

[the great him]

i gutted both the cats on my older 85 pickups, sound is way better, mileage went up, power was better, and they both improved on their smog readings... oh one of those motors is a LCE pro stroker that "supposedly" is off road only/ not for street use... cats in some vehicles do absolutely nothing. on our 3.4l 4runners im not so sure it would be a "good" idea, but as some members here have stated they have done this and had good results. its worth a try i guess, after all the rear o2 sensor does nothing to affect how the motor runs, it will only trigger the cel

 

[RonMAIDEN]

People with SC'd engines can't compare to the NA version since you will see gains (still pretty small plus it will be high up in the rpm band) but on an NA engine losing backpressure will kill ponies and torque down low and that's where you need it.
I've seen HP losses on Hondas after removing the cat and going with a bigger exhaust so I can't see any gains from removing the cat on a non SC'd 3.4.