The catalytic converter is responsible for the ignition and burning of engine exhaust gases which remain after the initial reaction occurs. This product became standard equipment in the U.S. for all vehicles with the 1975 model year. They help the exhaust gases become cleaner without a significant impact to the performance of the vehicle.
The catalyst in this device uses platinum and palladium to turn the initial exhaust created by the engine into gases which are less harmful to the environment. Each vehicle releases hydrocarbons, carbon monoxide, and nitrogen oxides during the combustion process. The catalytic converter then turns the carbon monoxide into carbon dioxide while the hydrocarbons become CO2 and water. The nitrogen oxides become oxygen and nitrogen.
Although this is a clear benefit compared to what is normally created, the high levels of carbon dioxide still create a greenhouse gas issue. If you remove the catalytic converter, then this conversion process disappears.
Here are some of the other pros and cons associated with the removal of a catalytic converter.
List of the Pros of Removing a Catalytic Converter
1. Your exhaust sounds better.
The catalytic converter works like a muffler on the average vehicle. Its job is to reduce the impact of the gases emerging from the engine due to the combustion and burning of fuel. This action muffles the sound of your exhaust in combination with the muffler on your vehicle. When the catalytic converter is no longer present, then the sound your vehicle emits is louder. (This is a possible “con” as well, depending on your viewpoint. See below.)
2. You can generate more horsepower without it.
Once the catalytic converter is removed from a vehicle, some models do experience a significant increase in power. This advantage occurs because the unit creates a source of back-pressure on the engine. It uses constriction as a way to impact the exhaust gases before they leave the vehicle’s system. Since the gas releases through the exhaust with added speed when the catalytic converter is not present, the engine can perform with its maximum potential since there is nothing left to hold it back.
3. You have access to more fuel options.
Up until the 1990s, fuel stations in the United States offered leaded and unleaded gasoline for sale. That’s because the presence of a catalytic converter eliminated the option of using a leaded fuel. When you take away this device, you have access to several additional high-performance fuel options for your engine that you wouldn’t be able to use otherwise. If you were to run leaded fuel through a catalytic converter, it would destroy the materials inside, rendering the vehicle useless.
4. You can operate the engine at a lower temperature.
When constriction occurs during the exhaust process, the extra work that the engine does to generate power creates more heat under the hood. By removing the catalytic converter, you remove this constriction, which means you can operate at a lower operating temperature. You’ll experience the benefits of less friction and load with the unit gone too, which can reduce the overall wear-and-tear on the vehicle over time.
5. You can achieve better gas mileage.
Since the catalytic converter places a strain on the engine with its constrictive design, it must work harder to achieve the same energy than it does without the device in place. Removing it lessens this burden, creating a net effect where the engine can perform significantly better without working as hard. That means you receive an improvement in fuel consumption which translates to an improvement in your overall fuel economy. Many have said the mpg gain is slight.
6. You can do it yourself.
Anyone with some decent car sense and a few tools can take care of removing their catalytic converter at home. All you need to do is follow these three steps.
• Uncouple the O2 sensor on your vehicle. You can do this if you have an O2 wrench available. Most auto parts stores have them or you can order one online.
• Pull off the catalytic converter next, separating it from the exhaust system. You’ll need to unbolt the device first, then slide it down your exhaust pipe. Some units are welded to the vehicle, so you’ll need to saw it off.
• Restore the exhaust system by creating a straight pipe to facilitate removal of the exhaust gases.
List of the Cons of Removing a Catalytic Converter
1. You cannot perform this action legally in several U.S. states.
You must follow a specific process to legally remove your catalytic converter in the United States. These guidelines are offered through 1986 rules that were issued by the Environmental Protection Agency. Several states, such as California, have strict laws on the books which prohibit the removal of a catalytic converter under most circumstances. Unless you know for certain what the outcome would be, speak with your mechanic about the pros and cons of removing this item before doing it on your own.
Federal law in the United States prohibits the removal of a catalytic converter which is functioning properly. A replacement converter is permitted if there is a documented failure of the original one. Serious fines may result if your vehicle is found to be without this device.
2. You may trigger a fault code in your vehicle.
Removing the catalytic converter may create a circumstance where you trigger a fault code in your vehicle. If you have a check engine light, then this will illuminate on your heads-up display. Although you can get around this issue on some vehicles by fitting a spacer on your downstream O2 sensor (the lambda sensor), there is a risk that normal functionality does not return. That would make it a challenge to track actual faults through this warning light.
3. You would create an emissions concern.
The goal of the catalytic converter is to remove the high levels of carbon monoxide created through fuel combustion to replace it with carbon dioxide. You want this device to scrub these gases for you because they contribute to global warming issues, acid rain, ocean acidification, and other forms of environmental damage.
There is the concern that the fumes from your exhaust could reach the vehicle cabin too. If you have an exhaust leak or you drive with the windows down, your lungs won’t appreciate the carbon monoxide. It may do more than induce a headache. It could create life-threatening situations in some circumstances.
4. You will create more noise when you drive.
Although the sound of an engine which is not held back by a catalytic converter sounds healthy, it can also become unhealthy from a noise perspective. If you have the windows down and the engine full, you might exceed 110 decibels without this device. Any noise above 85 decibels is potentially dangerous to your hearing health. Even if the noise isn’t bothersome after the unit is gone, the lack of noise suppression may interfere with conversations, becoming annoying after a lengthy drive, or cause noise complaints while you idle at home.(This is a possible “pro” as well, depending on your viewpoint. See above.)
5. You may use more fuel without a catalytic converter.
The catalytic converter does more than convert harmful gas into something less dangerous. It also squeezes a better fuel economy out of some vehicles. However, some people have reported that once they remove this device, they discover that their miles or kilometers per gallon actually go down. The most common explanation seems to be that they are burning more gas because their O2 sensors are not reading correctly and therefore requiring more fuel usage. Relatedly, there are reports that a notable amount of backpressure is lost.
6. You won’t pass a visual inspection for your vehicle.
If your vehicle must go through an emissions test, then it is essential to remember that there is a visual test in addition to the performance evaluate. When there isn’t a catalytic converter as part of your exhaust system, then your car will fail. Testers are usually required by law to report failures like this, which means an uncomfortable conversation will be waiting for you when you try to drive away. A failure may cause your vehicle to be impounded too.
7. You will lose your low-end torque without a catalytic converter.
The catalytic converters in the past were very restrictive because the exhaust coming from the combustion process was extremely toxic. Modern engines create less of an impact, which means the device creates almost the same effect as a straight pipe for the average vehicle on the road today that is less than 10 years old. If you decide to remove the catalytic converter, then you’ll experience a loss in your low-end torque while operating the vehicle. Your horsepower gains will be slightly better when you run full out. Since this is only legal for off-road vehicles, the benefits may not be the type you want.
The pros and cons of removing the catalytic converter from a vehicle involve performance and aesthetics at the cost of dangerous gas production. Most modern vehicles that are used for daily driving will see a minimal change to their performance by getting rid of this device. You’ll be paying more for fuel if it is gone while running the risk of fouling the air in your cabin. That’s why choosing this course of action is something that you do at your own risk.
About the Author
Brandon Miller has a B.A. from the University of Texas at Austin. He is a seasoned writer who has written over one hundred articles, which have been read by over 500,000 people. If you have any comments or concerns about this blog post, then please contact the Green Garage team here.
FAQs
What are the negative effects of removing a catalytic converter? ›
Engine fault codes will be generated, and engine performance will suffer as a result. While removing the catalytic converter will not harm the engine, you can expect a reduction in engine power as well as a reduction in fuel economy.
Is it beneficial to remove catalytic converter? ›Removal of catalytic converters from cars allows exhaust gases to exit their engines much faster and at higher levels. o Since catalytic converter removal allows for exhaust gases to exit a car's engine at increased speeds, engine back-pressure is reduced, which lessens engine strain.
What happens if I replace my catalytic converter with a straight pipe? ›However, it is illegal. If you install a straight pipe, often called a test pipe, you will fail all emissions tests or smog checks.
Does removing catalytic converter affect mileage? ›The catalytic converter opposes exhaust fumes. Removing it will make it easier for your engine to push out the exhaust, thus increasing your power output without increasing fuel consumption. The extra power will increase the efficiency of the engine, so your car will have a little better mileage.
Can you drive long distance without catalytic converter? ›Yes, you can drive without a catalytic converter. But it is unsafe and illegal to do so. Without the converter, your engine performance will suffer, and you can be exposed to a significant amount of toxic fumes.
How does a car sound without a catalytic converter? ›You'll notice a loud rumbling or roaring sound when you turn on the engine if your catalytic converter is missing. This sound gets louder when you hit the gas. The exhaust is not working correctly, so the vehicle also drives rougher than usual, often with a sense of sputtering as you change speed.
How much HP does a cat delete add? ›How much depends on how restrictive the catalytic converter was. It will typically be in a range between 5–20 hp, but don't expect big numbers from a small engine (hell, even some big motors don't get more than a 10–15 hp gain).
What are the disadvantages of Decat? ›One of the foremost disadvantages of decat pipes is the exponential increase in air pollution. Catalytic converters play a significant role in cleaning and removing toxins from your car's emissions. It oxidises unburned hydrocarbons and reduces the amount of nitrogen in the exhaust stream.
Will removing catalytic converter affect O2 sensor? ›Removing the catalytic converter is illegal and will seriously effect the emissions control systems, including the O2 sensors.
Is straight pipe better than catalytic converter? ›A straight pipe exhaust system helps your engine run more efficiently. That's because the backpressure created from the catalytic converter and muffler no longer exists. Less pressure on your engine results in more efficient operations, so you'll see a slight increase in fuel efficiency.
What to do after replacing catalytic converter? ›
To start the break-in procedure, start the car after you've replaced the cat. Let the car idle in place without applying any gas. When the engine warms up to its operating temperature, get inside and give the car enough gas to bump the RPMs to around 2500. Hold it there for 2 minutes and then release the gas.
Does straight piping increase HP? ›In some cases, straight piping can indeed increase horsepower and torque. This is especially true for high-performance engines that require a lot of airflows to produce power. By removing the muffler and catalytic converter, the engine can breathe more freely, increasing power.
Do you get better gas mileage without catalytic converter? ›But, while catalytic converters reduce emissions, they also reduce fuel efficiency. The back pressure created by a catalytic converter decreases the fuel thermal efficiency of an engine significantly. A fuel catalyst, on the other hand, both reduces emissions and increases fuel efficiency.
Do you get worse gas mileage without a catalytic converter? ›A common result of failure in the catalytic converter is a decrease in gas mileage. This is because if your catalytic converter becomes clogged, exhaust will become trapped in your car's engine.
Do you need to tune your car after removing catalytic converter? ›Short answer is, yes, you need a tune. Let me explain. Can you replace an exhaust with no catalytic converters on a stock vehicle (car)?
Will insurance cover a stolen catalytic converter? ›Is a stolen catalytic converter covered by insurance? If you have comprehensive coverage on your auto insurance policy, then you're typically covered against catalytic converter theft. Comprehensive coverage will typically pay to replace the stolen catalytic converter and repair any related damage from its removal.
Will a motor run without a catalytic converter? ›Technically, a car can function without a catalytic converter. However, this is not a sustainable long-term option.
Can missing catalytic converter cause misfire? ›Engine Misfires
An engine misfire is one of the surefire symptoms of a bad catalytic converter. Whenever your car has a misfire, it indicates incomplete combustion within the cylinder, implying that the catalytic converter isn't functioning effectively.
The catalytic converter forces the air and gases emitted by the engine to pass through tiny ducts. By removing it, the engine breathes more and develops more power. The sound is also enhanced and fuel consumption can be reduced by up to 10%, depending on the car model.
Does a cat delete make car louder? ›Absolutely. It will make the exhaust louder and/or change the exhaust pitch (lower tones). Although the muffler and the resonator(if equipped) take care of the majority of the noise, a catalytic converter also helps dull some of the noise. In most cases, it's not a lot however but definitely noticeable.
How illegal is a Decat? ›
The rules for emission control and catalytic converters are set by the Driver and Vehicle Licensing Agency or DVLA, and not the police. Emissions levels must be meet and if by fitting a decat pipe the vehicle no longer complies with the emissions standard set then it makes it illegal.
Why do people Decat their car? ›A Decat exhaust is a straight pipe that replaces your car's catalytic converter. The removal of a car's catalyst is favoured among car enthusiasts and tuners as it is an easy method to increase horsepower and engine performance.
Does catalytic converter reduce acceleration? ›Reduced Acceleration
The catalytic converter helps with the airflow into the engine by allowing exhaust gases through. If the catalytic converter gets clogged, the airflow to the engine is compromised, and you will find your vehicle's acceleration sluggish.
Thirdly, removing the catalytic converter may trigger a fault code which will illuminate the check engine light (assuming you have one). You can get around this by fitting a spacer on the downstream lambda (O2) sensor.
Can you drive without O2 sensors? ›Can I Drive My Car With A Bad Oxygen Sensor? We recommend against driving with a bad O2 sensor as the powertrain is not running on the correct fuel mixture. While it may perform fine in the beginning, if your engine is running rich and using too much fuel it might begin to clog the catalytic converter.
Can a catalytic converter destroy engine? ›What Are Potential Issues With a Catalytic Converter? Catalytic converters often last for 10 years or more, but they can become contaminated, clogged, overheated or physically damaged — leading to sluggish engine performance and, eventually, engine shutdown.
Why did someone cut off my catalytic converter? ›Money is the main reason catalytic converters are often stolen. They contain three metals that aid in the chemical reaction that makes exhaust pollutants less harmful: platinum, palladium and rhodium. The prices of these metals have risen dramatically during the early 21st century.
Will removing catalytic converter throw a code? ›Thirdly, removing the catalytic converter may trigger a fault code which will illuminate the check engine light (assuming you have one). You can get around this by fitting a spacer on the downstream lambda (O2) sensor.
Can you replace a catalytic converter with a muffler? ›Can I replace the catalytic converter with a straight muffler pipe? No. You will fail an emissions test if you do that.
Can the catalytic converter affect the transmission? ›A clogged catalytic converter makes the engine work harder, which in turn makes it difficult to shift the transmission. In regards to air, a bad O2 sensor or dirty mass air flow sensor will also cause the gears to stick.
Does revving engine clean catalytic converter? ›
Answer: Unfortunately there really is no way of clean out a catalytic converter. There is a misconception of revving the engine hard to blow high volumes of exhaust through the tailpipe in an effort to dislodge carbon buildup within the CAT, and at times vehicle owners are able to prove this correct.
What to do after removing catalytic converter? ›You will need to get a tune after removing your catalytic converter. If your car isn't tuned for serious performance gains, the cat delete won't do much. One of the reasons behind that is the ECU uses information from the oxygen sensors from before and after the catalytic converter to fine-tune performance.
How to get rid of check engine light after removing catalytic converter? ›You could also just take out the O2 sensor past the catalytic converter and strap it to the frame still plugged up. Then you can plug the hole in your exhaust with a bolt of matching threads. By removing the sensor it will only read clean air.
Will check engine light come on if catalytic converter is stolen? ›Check Engine Warning
The first time that you start your automobile after the catalytic converter has been stolen the check engine light will turn on. It will remain on until you replace the catalytic converter and repair any exhaust system damage.
Is a stolen catalytic converter covered by insurance? If you have comprehensive coverage on your auto insurance policy, then you're typically covered against catalytic converter theft. Comprehensive coverage will typically pay to replace the stolen catalytic converter and repair any related damage from its removal.
What happens to your car when someone takes your catalytic converter? ›If your converter has been stolen, you're likely to notice right away: Without the converter, your car will be much noisier than usual. Most cars will run without a catalytic converter, though it's inadvisable to do so for longer than necessary.
Will a gutted cat cause a check engine light? ›Yes, if you gut it or straight-pipe it, the downstream O2 sensor after the cat would show the same/similar reading as the upstream O2 sensor before the cat. This would trigger a check engine code for catalytic converter efficiency below threshold.
Can you turn off O2 sensors? ›Re: Turn off downstream O2 sensors? No, a "tuner" can turn them off, though many refuse now due to the recent EPA crackdowns.
How long does it take the check engine light to go off after replacing the catalytic? ›In most cases, successfully repairing the issue that caused your light to come on will cause the check engine light to turn off automatically—but only after 10 to 20 “cycles”.