Hello Guys/Gals
Just wondering has anyone removed their catalytic converter? Any power increase? Will it make my check engine light go on? I know it illegal here in California but who cares I know of plenty of shops where I can get this done.

I really dought that that will be a good idea since its directly linked to the vehicle computer. i also dont think you will get an increase thats worth the risk of damaging your engine. From what i hear this migh actually lower your low end power. Any one the true tech specs on this.

Sounds like a bad idea to me.

http://www.titantalk.com/forums/titan-performance-modifications/55857-without-catalytic-converters.html

http://www.titantalk.com/forums/titan-engine-transmission-drivetrain/54907-catalytic-converter.html

Well, not having looked under my Mada yet to see what the set-up is, I can tell you a bit about removing Cats on other vehicles.

I will use my Mustang (2001) as the example, but most all vehicles work in the same manner. There are usually two sets of O2 sensors on a vehicle, those before the cats and those at or after the cats. Those that are before the cats read the exhaust gases to adjust the air fuel ratios accordingly. Those after the cats read exhaust gases in the same manner, but the computer is programmed to read them as “cats working / not working”. That’s the basics.

Now with that being said, you can remove the cats on a vehicle (note; this is a federal and usually a local offense and is illegal to do so, I am not condoning this action) to get an increase in HP in the upper ranges or the RPM’s. You will loose some low end torque, but usually not enough to really notice it b/c you will get into the upper RPM’s faster. Removing the cat will make the Check Engine light come on, but you can get around this by adding a MIL eliminator to your O2 sensor.

More on O2’s, so you can understand what a MIL eliminator is.

The 02 sensor can be considered a small battery that has an operating range of 0 to 1 volt when fully warmed up to 600+F. Its voltage depends on the amount of oxygen in the exhaust stream. The ideal range is between .3 - .6 volts, this tells the computer that everything is working as it should (for front O2’s, it says that air fuel ratios are good, for rear O2’s it says that the cats are operating within normal ranges).

The exhaust of the gasoline Powered engine typically contains up to 2% oxygen. The Sensor's output voltage depends on the oxygen content of the exhaust stream. That is, if the exhaust has 2% oxygen, it is lean. This produces a low voltage, below .3 volts (300millivolts). If the exhaust has near 0% oxygen, it is rich. This produces a high voltage, above .6 volts (600millivolts). These voltages are sent to the computer and it reacts by adjusting the air/fuel ratio. This is commonly known as the 02 feedback system and when this system is operating it is said to be in "closed loop". When it is not operating, meaning the computer is not reading and responding to the oxygen sensor, it is said to be in "open loop".

In order to read the 02 sensor, most computers send out a certain voltage to the output terminal of the sensor. This is typically around 450 miliVolts. Since we know that the sensor sends low voltage (under 300mV) when a lean condition is present and high voltage (over 600mV) when rich condition is present, the computer can count the number of times the sensor crosses the 450mV mark. Cross-counts are the number of times the 02 sensor crosses 450mv. A scanner can "look" at this for you. Even though you can't see the numbers of cross counts without a scanner, you can use a digital voltmeter to watch the open/closed loop system operate.

Now, a MIL eliminator is a 1/4-1/2 watt resistor and a capacitor. It takes the output provided by the sensor and reduces the output by 25-50% bringing the "new" output down to acceptable levels (The resistor “cuts” the signal by 25-50% and the capacitor smooths it out). So, if you have a good working sensor and no cats, you’re going to read above 600mV, the MIL will reduce that output to within the 300-600mV range (the acceptable range). One thing to note, if you use MIL’s, you have to have a good working O2 sensor, so if you truck has any mileage on it or its possible that they may be bad or nearing their life span (~75k, but will start to deteriorate and slow down as soon as 35-50k) then replace it with a new one.


Sorry this is so long, I copied most of it from a post of mine on the Ford-truck forums where I Used to board with my old Expy. :p

Sounds like a bad idea to me.

http://www.titantalk.com/forums/titan-performance-modifications/55857-without-catalytic-converters.html

http://www.titantalk.com/forums/titan-engine-transmission-drivetrain/54907-catalytic-converter.html

Removing a cat or cats will give you a power increase. On my stang, this netted me ~15hp according to the dino. Not much, but 5 here 15 there, 10 overthere, gets you somewhere.

To add to the second post above, you WILL loose power when you have a clogged exhaust, as there is nowhere for it to flow but back to the engine........:(

Dang Bro, how much HP do you need and what are you doing? I think we got pleanty enough HP with the Armada to do what we need and then some. Taking off the CC is not a good idea for the way these vehicles are engineered. Older vehicles showed improvement because the cat was restrictive to old engineering. Today it is not a wise decision.

just my opinion!

Removing cats can give you better flow. If that is the restriction point, you will get power. Also, you will need to relocate the O2 bungs for the oxygen sensors. That said, I'd probably install high flow cats instead. These do the same emissions cleaning as standard cats, are legal, but will not restrict flow. They are a little more of a PITA to put in than a straight pipe, but a much better way to go. Also, I would say you'd have to replace exhaust and put in long tube headers before the cats became the choke point. Making a freer flowing exhaust will usually give you mid to high range power sacrificing low end torque due to the lower back pressure. Hope this helps.

Hi-flow cats are not legal! The only cats that are legal are stock replacements.

Removing the cats will not harm the vehicle in any way and there are many ways to keep the CEL from comeing on. Lookin gfor HP removing the cats is probally the cheaps and easiest way to do it...but has it draw backs.

And back pressure is not the correct term to use as it is exhaust volecity(sp).
Back pressure is bad!

What happens on one vehicle doesn't mean it will do the same for all vehicles. I have removed the cats on all of my cars/trucks were I was looking for all the HP/TQ I could get and never seen a loss in low in.

My friend tried to remove his pontiac catalytic converter (http://www.catalyticonverters.com/pontiac_catalytic_converter.html) for he know that it will give more power to his car. A week ago, when he is riding his car alone, he notice of low powering. He send his car to the mechanic. The mechanic told him about the results of removing catco...and its bad!!!

That is why I don't believe in removing catalytic converter. And one thing guys... cat co is a must, we really need to cooperate with the environment. That is only my opinion.

Welcome to the Club tanggusloy!!! I'm assuming you posted the link because of the history educating information found on the pages. I found the info on these pages pretty informative.

I did remove the cat on an '83 Z28 that I had rebuilt the 305cu with a larger cam, oversized flat heads, and installed a shift kit and I was toasting any '70's - '80's Vettes in 89-91. I had to stop and wait for the cops to catch up to me one night before they called out a helicopter because they couldn't keep up. I was lucky and got out of the ticket because I was going too fast for their radar to register my speed. Removing the Cat on that car did help and I never saw any problems but on today's cars I would definitely be concerned about engine damage.

http://www.catalyticonverters.com

http://www.catalyticonverters.com/nissan_catalytic_converter.html

A cat is not vital to the engine at all. It is a part only too keep emmissions clean.

Having seen many cars do it I can't remember one that lost power from it.
If there was it was probally from gutting them with is not very smart too do in the first place.

Removing a cat or cats will give you a power increase. On my stang, this netted me ~15hp according to the dino. Not much, but 5 here 15 there, 10 overthere, gets you somewhere.

To add to the second post above, you WILL loose power when you have a clogged exhaust, as there is nowhere for it to flow but back to the engine........:(

I agree....When I removed the cats on my 03 cobra I gained a good amount of RWHP....but not 100% how much. Removing the cats will give more HP, in the case of the armada I just don't know how much.

Thanks for the welcome Pops! :)

"A cat is not vital to the engine at all. It is a part only too keep emmissions clean. "

I would still rather not remove my cat. I am more for less emissions.