Exhaust System: Description and Operation
EXHAUST SYSTEMWARNING: THE NORMAL OPERATING TEMPERATURE OF THE EXHAUST SYSTEM IS VERY HIGH. THEREFORE, NEVER WORK AROUND OR ATTEMPT TO SERVICE ANY PART OF THE EXHAUST SYSTEM UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE TAKEN WHEN WORKING NEAR THE CATALYTIC CONVERTER. THE TEMPERATURE OF THE CONVERTER RISES TO A HIGH LEVEL AFTER A SHORT PERIOD OF ENGINE OPERATION TIME.
The exhaust system consist of two front close coupled catalytic converters. Both converters attach directly to the exhaust manifold using a V-Band clamp. The exhaust down pipes exit the converters and connect into the front resonator. The front resonator, intermediate pipe, and muffler are one single module. The rear resonator and tailpipe connect to the muffler outlet. The upstream oxygen sensors are located in each exhaust manifold. The downstream oxygen sensors are located at the rear of each catalytic converter.
CATALYTIC CONVERTERS
There is no regularly scheduled maintenance on any Chrysler catalytic converter. Excessive heat may cause bulging or other distortion, but excessive heat will not be the fault of the converter. A fuel system or ignition system malfunction that permits unburned fuel to enter the converter will usually cause overheating. If a converter is heat damaged, correct the cause of the damage at the same time the converter is replaced. The entire converter must be replaced. Inspect all other components of the exhaust system for heat damage. Unleaded gasoline must be used to avoid damage to the catalyst core.
CAUTION: Due to exterior physical similarities of some catalytic converters with pipe assemblies, extreme care should be taken with replacement parts. There are internal converter differences required in some parts of the country (particularly vehicles built for a State with strict emission requirements).
EXHAUST GAS RECIRCULATION (EGR)
To assist in the control of Oxides Of Nitrogen (NOx) in engine exhaust, all engines are equipped with an Exhaust Gas Recirculation (EGR) system. The use of inert exhaust gas to dilute incoming air/fuel mixtures, lowers peak flame temperature during combustion, thus limiting the formation of NOx.
Exhaust gases are routed through a tube from the exhaust manifold to the intake manifold adapter, where they are metered by the EGR valve into the intake system. Refer to Powertrain Management; Emission Control Systems for a complete description, diagnosis and the proper service procedures.
HEAT SHIELDS
Heat shields are needed to protect both the car and the environment from the high temperatures developed in the vicinity of the catalytic converters. Each catalytic converter has an integral heat shield attached to it and is not to be removed.
CAUTION: Avoid application of rust prevention compounds or undercoating materials to exhaust system heat shields on cars if equipped. Light over spray near the edges is permitted. Application of coating will greatly reduce the efficiency of the heat shields resulting in excessive floor pan temperatures and objectionable fumes.
The combustion reaction caused by the catalyst releases additional heat in the exhaust system. Causing the temperature to increase in the area of the reactor under severe operating conditions. Such conditions can exist when the engine misfires or otherwise does not operate at peak efficiency. Do not remove spark plug wires from plugs or by any other means short out cylinders if exhaust system is equipped with catalytic converter. Failure of the catalytic converter can occur due to temperature increases caused by unburned fuel passing through the converter.
The use of the catalysts also involves some non-automotive problems. Unleaded gasoline must be used to avoid poisoning the catalyst core. Do not allow engine to operate above 1200 RPM in neutral for extended periods over 5 minutes. This condition may result in excessive exhaust system/floor pan temperatures because of no air movement under the vehicle.