Land Rover Defender: Exhaust System - Description and Operation

DESCRIPTION AND OPERATION

COMPONENT LOCATION

COMPONENT LOCATION - 1 OF 1

NOTE: Vehicle with 5 doors is shown. Vehicle with 3 doors is similar.

1. Ring flange to turbocharger
2. Flexible coupling
3. Resonator
4. Mounting rubber (quantity 2)
5. Rear silencer
6. Mass damper
7. Mounting rubber (quantity 2)
8. Clamp (quantity 2)
9. Main catalytic converter or Main catalytic converter/ Gasoline Particulate Filter (GPF)
10. Pre catalytic converter

OVERVIEW

The Ingenium I4 2.0L petrol exhaust system is manufactured from stainless steel. The exhaust system attaches to the underside of the vehicle body with 4 mounting rubbers. The mounting rubbers are located on hanger brackets that are welded to the exhaust system. The mounting rubbers locate on adjacent hanger brackets which are bolted to the underside of the vehicle body.

There are 2 variants that are available on the Ingenium I4 2.0L petrol exhaust system:

• Vehicles without GPF
• Vehicles with GPF.

DESCRIPTION

The Ingenium I4 2.0L petrol exhaust system comprises 3 separate sections:

• An exhaust front section
• An exhaust center section
• An exhaust rear section.

EXHAUST FRONT SECTION - VEHICLES WITHOUT GASOLINE PARTICULATE FILTER

1. Ring flange to turbocharger
2. Gasket
3. Threaded hole - Pre catalyst Heated Oxygen Sensor (HO2S)
4. Pre catalytic converter
5. Threaded hole - Mid catalyst HO2S
6. Main catalytic converter
7. Threaded hole - Post catalyst HO2S
8. Support bracket

The exhaust front section comprises pre and main catalytic converter. The catalytic converters are emission control devices that reduce the amount of pollutant gases released into the atmosphere.

The inlet pipe of the pre catalytic converter is connected to the turbocharger outlet housing. The pre catalytic converter is sealed to the turbocharger by a mica gasket and an exhaust clamp. Immediately after the flange the pipe contains a threaded hole for the installation of the pre catalyst HO2S. The mid catalyst HO2S is located between the pre and the main catalytic converter. The main catalytic converter is secured to a transmission mounted bracket by a strap. After the main catalytic converter, there has a threaded hole to install the post catalyst HO2S.

The pre, mid and post catalyst HO2S monitors the exhaust gases leaving catalytic converter. The pre catalyst HO2S monitors the gases leaving the engine. The mid catalyst HO2S monitors the gases leaving the pre catalytic converter.

The post catalyst HO2S monitors the gas leaving the main catalytic converter.

The information from the HO2S is used by the Powertrain Control Module (PCM) to calculate how much fuel injection is required to maintain the correct air fuel ratio. Maintaining the correct air fuel ratio for all engine operating conditions is important to optimize fuel consumption and exhaust emissions. The information is also used to monitor the performance of the catalytic converters.

EXHAUST FRONT SECTION - VEHICLES WITH GASOLINE PARTICULATE FILTER

1. Ring flange to turbocharger
2. Gasket
3. Threaded hole - Pre catalyst HO2S
4. Pre catalytic converter
5. Threaded hole - Mid catalyst HO2S
6. Main catalytic converter/ GPF
7. Threaded hole - Post catalyst HO2S
8. Support bracket
9. Pressure pipe - Exhaust back pressure sensor

On vehicles equipped with GPF, the exhaust front section comprises of pre catalytic converter and the main catalytic converter/ GPF. The catalytic converter converts toxic gases and pollutants in exhaust gas to less toxic pollutants.

The inlet pipe of the pre catalytic converter is connected to the turbocharger outlet housing. The pre catalytic converter is sealed to the turbocharger by a mica gasket and an exhaust clamp. Immediately after the flange the pipe contains a threaded hole for the installation of the pre catalyst HO2S). The mid catalyst HO2S is located between the pre catalytic converter and the main catalytic converter/ GPF. The main catalytic converter/ GPF is secured to a transmission mounted bracket by a strap. After the main catalytic converter/ GPF, there has a threaded hole to install the post catalyst HO2S.

The GPF traps the particulate matter in the exhaust gas that the direct injection combustion process produces.

A pressure pipe for the exhaust back pressure sensor is located between the mid catalyst HO2S and the main catalytic converter/ GPF. The exhaust back pressure sensor measures the exhaust gas pressure upstream of the main catalytic converter/ GPF and transmits the information to the PCM. The exhaust gas back pressure information is used by the PCM to calculate soot load in the main catalytic converter/ GPF. When an increased level of back pressure is identified, the PCM begins regeneration of the GPF.

EXHAUST CENTER SECTION

NOTE: Vehicle with 5 doors is shown. Vehicle with 3 doors is similar.

1. Clamp (quantity 2)
2. Mounting rubber (quantity 2)
3. Resonator
4. Flexible coupling

The exhaust center section comprises of 1 inlet, 1 outlet pipe,1 flexible coupling and 1 resonator.

The inlet pipe of the exhaust center section is secured to the exhaust front section outlet pipe with 1 clamp.

The exhaust center section is attached to the underside of the body with 2 mounting rubbers. The mounting rubbers attach to hanger brackets that are welded to the system. The mounting rubbers locate on corresponding hanger brackets which are bolted to the underside of the vehicle body.

EXHAUST REAR SECTION

NOTE: Vehicle with 5 doors is shown. Vehicle with 3 doors is similar.

1. Mounting rubber (quantity 2)
2. Outlet pipe (quantity 2)
3. Rear silencer
4. Mass damper
5. Inlet pipe

The rear exhaust section has 1 silencer which has 1 inlet and 2 outlet pipes. The outlet pipes direct exhaust gases away from the rear of the vehicle.

The rear exhaust section is supported by 2 mounting rubbers and 1 mass damper. The mounting rubbers are attached to 2 hanger brackets bolted to the underside of the vehicle body. A mass damper is installed on the rear silencer left mounting point to reduce the Noise, Vibration and Harshness (NVH) characteristics of the exhaust system.

In production the resonator and the rear silencer are installed as one component. In service the rear silencer can be replaced independently.

OPERATION

CATALYTIC CONVERTER

The catalytic converter reduces the carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx) content of the exhaust gases. In the catalytic converter the exhaust gases pass through honeycombed ceramic elements whose surface is treated with a special deposit of washcoat containing catalytic elements. The washcoat also increases the surface area of the ceramic elements by a factor of approximately 7,000.

The palladium and rhodium are on the surface of the washcoat. The palladium facilitates the oxidation of HC and CO to form water vapor (H2O) and carbon dioxide (CO2). The rhodium facilitates the reduction of the NOx into molecular Nitrogen (N2) by extraction of the O2 from the NOx molecules. The chemical process of Oxidation of CO, HC and reduction of NOx occurs according to the level of oxygen in the exhaust flow. Maximum efficiency (best CO /hydrocarbons oxidation, best NOx reduction) occurs at Lambda 1.

GASOLINE PARTICULATE FILTER

The GPF system reduces particulate matter emissions to levels sufficient to meet current emission standards. The GPF consists of a stainless steel housing which contains a synthetic cordierite based ceramic filter. The ceramic filter has a catalytic coating and is able to withstand the very high operating temperatures required for regeneration.

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