TWC Operation

As engine exhaust gases flow through the converter passageways, they contact the coated surface which initiate the catalytic process. As exhaust and catalyst temperatures rise, the following reaction occurs:

• Oxides of nitrogen ( NOx) are reduced into simple nitrogen (N2) and carbon dioxide (CO2)

• Hydrocarbons (HC) and carbon monoxide (CO) are oxidized to create water (H2O) and carbon dioxide (CO2)

Catalyst operating efficiency is greatly affected by two factors; operating temperature and feed gas composition. The catalyst begins to operate at around 550' F.; however, efficient purification does not take place until the catalyst reaches at least 750' F. Also, the converter feed gasses (engine-out exhaust gases) must alternate rapidly between high CO content, to reduce NOx emissions, and high O2 content, to oxidize HC and CO emissions.

Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook


Post a comment