Three-Way Catalytic Converter (TWC) Operation

Three-Way Catalytic Converter (TWC):

CONSTRUCTION
The catalytic converter is a monolythic three-way device that uses catalytic compounds applied to an integrally constructed honeycomb carrier surface in the center of the exhaust pipe.

Converter Efficiency VS. Stoichiometric Fuel/Air Ratio:

OPERATING CONDITIONS
The catalytic converter removes CO, HC, and NOx from the exhaust stream most effectively at the stoichiometric (14.7 to 1 plus or minus 1%) fuel-air mixture ratio and at temperatures between 400 to 800 degrees C (750 to 1500 degrees F).

Engine malfunctions, such as misfiring, can result in exhaust temperatures exceeding 1400 degrees C (2500 degrees F). These extremely high temperatures can cause the substrate to melt, resulting in destruction of the converter. The use of leaded fuels should also be avoided. Lead in the exhaust residue coats the catalyst, preventing catalytic action. Excessive oil residues in the exhaust can also poison the catalyst.