What happens when you remove the catalytic converter?

Answer 1

If you remove the catalytic converter you will be in violation of Federal and some state environmental regulations. The vehicle will run just fine, but you'll pay if you're caught.

Removing the catalytic converter reduces back pressure on the engines exhaust and can increase the engines performance by a small amount, The converter burns off small amounts of excess fuel that escape through the exhaust and other gases to reduce the pollution levels produced by the engine. eventually the honeycomb material in the converter may become clogged and cause problems with the engine performance ,it then needs removed and replaced. However since some converters can cost hundreds of dollars there are millions of quick fix mechanics that remove the old converter and chisel out the honeycomb material leaving the converter housing intact and the inside empty and then they place the converter back on the exhaust system. The vehicle will fail an emissions test but will run just fine otherwise.

If the car is a late model with a computer and oxygen sensors, the computer will adjust the air/fuel ratio to try to get the now non existent converter to work. This can really hamper performance and economy. It will also turn the check engine light on.

Additional Note:: If a non-functional converted is used you must by pass the oxygen sensor/s to avoid check engine lights and keep the computer from adjusting the fuel/air mixture to compensate for the empty converter,some models have an oxygen sensor both before and after the converter,this easily done by purchasing a dummy oxygen sensor/simulator that tells the computer the mixture is with in normal limits these can be found at any auto parts store under the off road parts..You can also just unclip the oxygen sensor wire and loop a resistor between the terminals of the wiring to achieve the same result however the size of the resistor varies with each make and model..