Viper SRT-10 V10-8.4L (2008)
Catalytic Converter: Description and Operation
OPERATION
The three-way catalytic converter simultaneously converts three exhaust emissions into harmless gases. Specifically, HC and CO emissions are converted
into water (H2O) and carbon dioxide (CO2). Oxides of Nitrogen (NOx) are converted into elemental Nitrogen (N) and water. The three-way catalyst is
most efficient in converting HC, CO and NOx at the stoichiometric air fuel ratio of 14.7:1.
The oxygen content in a catalyst is important for efficient conversion of exhaust gases. When a high oxygen content (lean) air/fuel ratio is present for an
extended period, oxygen content in a catalyst can reach a maximum. When a rich air/fuel ratio is present for an extended period, the oxygen content in
the catalyst can become totally depleted. When this occurs, the catalyst fails to convert the gases. This is known as catalyst "punch through."
Proper catalyst operation is dependent on its ability to store and release the oxygen needed to complete the emissions-reducing chemical reactions. As a
catalyst deteriorates, its ability to store oxygen is reduced. Since the catalyst's ability to store oxygen is somewhat related to proper operation, oxygen
storage can be an indicator of catalyst performance. Refer to the appropriate powertrain diagnostic procedure for diagnosis of a catalyst-related
Diagnostic Trouble Code (DTC).
The combustion reaction caused by the catalyst releases additional heat in the exhaust system. Under severe operating conditions, this causes temperature
increases in the area of the reactor. Severe operating conditions can exist when the engine misfires or otherwise does not operate at peak efficiency.
NOTE: If the exhaust system is equipped with a catalytic converter, do not remove spark plug wires from plugs, or short out cylinders by any
other means.
The catalytic converter can fail because of temperature increases caused by unburned fuel passing through the converter. This deterioration of the
catalyst core can result in excessively high emission levels, noise complaints, and exhaust restrictions.
Unleaded gasoline must be used to avoid poisoning the catalyst core. Do not operate the engine in neutral above 1200 RPM for extended periods over 5
minutes. Because there is no air movement under the vehicle, excessive exhaust system/floor pan temperatures may result.
CAUTION: Due to exterior physical similarities of some catalytic converters with pipe assemblies, extreme care should be taken with
replacement parts. Internal converter differences are required in some parts of the country (particularly vehicles built for states with strict
emission requirements).
