Exhaust System: Description and Operation

Exhaust System

The 2.5L exhaust system consists of:

- a one-piece catalytic converter manifold (hybrid only).
- an exhaust manifold (except hybrid).
- an exhaust flexible pipe.
- an underbody catalytic converter.
- a Catalyst Monitor Sensor (CMS) mounted to the underbody catalytic converter.
- a production muffler and tail pipe assembly.
- isolators installed on the body and muffler hangers.

The 3.0L exhaust system consists of:

- a one-piece catalytic converter manifold.
- a RH exhaust manifold-mounted catalytic converter.
- an exhaust flexible pipe.
- an underbody catalytic converter.
- a production muffler and tail pipe assembly.
- isolators installed on the body and muffler hangers.

The 3.5L exhaust system consists of:

- two exhaust manifold-mounted catalytic converters.
- an exhaust Y-pipe.
- a resonator and flex assembly.
- a production muffler and tail pipe assembly.
- isolators installed on the body and muffler hangers.

The exhaust system provides an exit for exhaust gases and reduces engine noise by passing exhaust gases through the catalytic converters, a muffler assembly and resonator. Rubber exhaust hanger isolators attach the exhaust system to the hangers welded on the body.


Catalytic Converter

The catalytic converter plays a major role in the emission control system. The catalytic converter operates as a gas reactor. Its catalytic function is to speed the heat-producing chemical reaction of components in the exhaust gases in order to reduce air pollutants.

The catalyst material inside the catalytic converter consists of a ceramic substrate.

The catalytic converter is designed to provide a long life. No maintenance is necessary for the catalytic converter.

Precautions

NOTICE: Do not use leaded fuel in a vehicle equipped with a catalytic converter. In a vehicle that is continually misfueled, the lead in the fuel will be deposited in the catalytic converter and completely blanket the catalyst. Lead reacts with platinum to "poison" the catalyst. Continuous use of leaded fuel can destroy the catalyst and render the catalytic converter useless. The addition of lead to the catalytic converter can also solidify the catalyst, causing excessive back pressure in the exhaust system and possibly causing engine damage.

NOTICE: Extremely high temperatures of 1,100°C (2,012°F) or above due to misfiring or an over-rich fuel/air mixture will cause the ceramic substrate to sinter or burn, destroying the catalytic converter. Do not continue to operate the vehicle if the engine is misfiring, there is a power loss or other unusual operating conditions, such as engine overheating and backfiring.

Some exhaust fasteners must be discarded and new ones installed as indicated in the procedures. Also, any damaged or heavily corroded fasteners should be discarded and new ones installed. Some exhaust fasteners are of a prevailing torque design. Use only new fasteners with the same part number as the original. Torque values must be used as specified during reassembly to make sure of correct retention of exhaust components.


Sound Insulators and Shields

Sound insulators and shields, attached to the underbody, protect the vehicle from exhaust system heat and should be inspected at regular intervals to make sure they are not dented or out of position. If a sound insulator and shield is damaged or shows evidence of deterioration, install a new insulator and shield. The sound insulators and shields for the muffler, muffler pipe, resonator and catalytic converter pipe are installed separately.