Exhaust System: Description and Operation

Exhaust System - Vehicles With: Supercharger

COMPONENT LOCATION

Exhaust System:

OVERVIEW
The exhaust system is fabricated from stainless steel and is supplied as four separate assemblies:
- A LH front section incorporating a catalytic converter
- A RH front section incorporating a catalytic converter
- A center section incorporating 2 silencers
- A rear section including the main silencer box.

Each section of the exhaust system is available as a service replacement.

The exhaust system is attached to the underside of the body with five mounting rubbers, two on the center section and three on the rear muffler. The mounting rubbers attach to the exhaust system via stainless steel hangers and brackets. The mounting rubbers locate on corresponding hangers which are attached to the underside of the vehicle body. The system is routed along the center of the chassis before splitting near the rear differential prior to entering the main exhaust silencer at the rear of the vehicle.

To reduce the carbon monoxide and hydrocarbons content of the exhaust gases, a catalytic converter is integrated into each of the front pipes of the exhaust system.

ACTIVE EXHAUST SYSTEM
The rear muffler unit incorporates an active exhaust system. The active exhaust system is designed to give a more sporty sound and also reduces the back pressure in the exhaust system by opening a valve in the second exhaust outlet pipe.

The active exhaust system is controlled by the ECM. The ECM controls a vacuum control valve which in turn applies a vacuum to the active exhaust valves. The vacuum system comprises:
- A vacuum reservoir
- A vacuum pump
- A control solenoid
- A Vacuum check/non return valve
- A vacuum restrictor valve located in the vacuum line just above the check valve

The vacuum restrictor valve allows air back into the vacuum lines to allow the active exhaust valves to open more slowly than they close.

Exhaust System Vacuum Control System







The active exhaust valves are opened in response to engine speed and throttle angle. At startup the valve is always opened to give an enhanced sound. The following table details when the valves are open and when they are closed.

Active Exhaust Valve Opening Strategy







NOTE: At engine speeds above 4000 RPM the valves are open independent of throttle angle.

The active exhaust valves are normally open until a vacuum is applied to them. The active exhaust valves are either open or closed they do not partially open.

Exhaust Gas Flow