A catalytic converter should NEVER go bad unless something causes it such as a RICH or a LEAN condition. What is a "RICH OR A LEAN CONDITION"?
Yes, a catalytic converter can influence the smell of exhaust fumes. If the converter is functioning properly, it helps reduce harmful emissions and can eliminate some of the rich, fuel-like odors. However, if the catalytic converter is failing or there's an issue with the engine, such as incomplete combustion or fuel mixture problems, it may lead to a richer smell in the exhaust fumes. In such cases, addressing the underlying issues can help mitigate the odor.
A partially clogged converter will cause this. Also an overly rich fuel/air mixture or a cylinder misfire is a cause.
You either removed the catalytic converter or you are running too rich.
Too rich of an air/fuel mixture of one of more cylinders missing and not completely burning the fuel.
The catalytic converter usually has an Oxygen Sensor before and after the converter. The hot exhaust gases of the exhaust heat up a catalystic and the voltage is proportional to Oxygen. By measuring before and after the catalytic converter, you have a sense if the Catalytic converter is working correctly in cleaning up the exhaust. The exhast to be cleaned up correctly requires the PCM to sometimes run Lean fuel mixture, to clean up NOx, and sometimes Rich mixture to clean up HC (Hydrocarbons). So PCM cycles the fuel mixture between rich and lean many times in the process of driving, so that to get optimal efficiency of the catalytic converter. However, if you have a vacuum leak, your engine will run LEAN and the PCM will compensate and force it to run rich instead. After a while, by running rich too much, you are throwing unburned fuel into the exhaust pipe, causing Catalytic converter to become Red hot and causing it to fail. So in short, running Rich, not lean, can cause converter failure.
Fuel/air mixture too rich, engine misfire, or damage.
If it is glowing red it is partially clogged or the engine is running rich.
The converter is clogged or the engine is running way to rich or has a misfire.
Clogged converter, running too rich or a misfiring plug.
It is partially clogged, cylinder miss, or the fuel/air mixture is too rich.
Sensor 1 (before the catalytic converter) adjusts the fueling based on sensing if the engine is burning fuel rich or lean. The post-converter sensor detects if the converter is operating properly by looking for a difference in readings