Exhaust System: Overview Jeep Compass I рестайлинг 2

Scheme 1

The FWD gas engine exhaust system components consist of a catalytic converter, intermediate pipe, muffler, clamps and support isolators.

Scheme 2

The AWD gas engine exhaust system components consist of a maniverter, under floor catalytic converter, intermediate pipe, muffler, clamps and support isolators.

DESCRIPTION

The combination exhaust manifold/catalytic converter is attached to the intermediate pipe using fasteners and a gasket for sealing.

The stainless steel catalytic converter body is designed to last the life of the vehicle. Excessive heat can result in bulging or other distortion, but excessive heat will not be the fault of the converter. If unburned fuel enters the converter, overheating may occur. If a converter is heat-damaged, correct the cause of the damage at the same time the converter is replaced. Also, inspect all other components of the exhaust system for heat damage.

Unleaded gasoline must be used to avoid contaminating the catalyst core.

FWD vehicles use a catalytic converter located after the exhaust manifold and before the I-Pipe/Muffler assembly.

AWD vehicles use a maniverter and an under floor catalytic converter. The under floor catalytic converter is located between the maniverter and the I-Pipe/muffler assembly.

Diesel engine vehicles use a catalytic converter located between the turbocharger and the I-Pipe/Muffler assembly.

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 Nitrogen (N) and Oxygen. 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."

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 used as an indicator of catalyst performance. Refer to the appropriate Diagnostic Information for diagnosis of a catalyst related Diagnostic Trouble Code (DTC).

The combustion reaction caused by the catalyst releases additional heat in the exhaust system, causing temperature increases 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. Failure of the catalytic converter can occur due to 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 ruining 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.

The flex joint allows flexing as the engine moves, preventing breakage that could occur from the back-and-forth motion of a transverse mounted engine.

Scheme 3

1. Raise vehicle on hoist and apply penetrating oil to band clamp fastener of component being removed. NOTE: Do not use petroleum-based lubricants when removing/installing muffler or exhaust pipe isolators as it may compromise the life of the part. A suitable substitute is a mixture of liquid dish soap and water.
2. Remove I-Pipe/Muffler assembly. Refer to «MUFFLER, EXHAUST, REMOVAL»(ref-612703-S09683297992014043000000) .
3. Disconnect oxygen sensor electrical connectors. NOTE: If spherical gasket is to be reused, mark orientation.
4. Remove flange bolts (3), springs and spherical gasket.
5. Remove under floor catalytic converter (4) from maniverter or catalytic converter assembly (1).
6. Clean ends of pipes to assure mating of all parts. Discard broken or worn isolators, rusted or overused clamps, supports, and attaching parts.

Note. When replacement is required on any component of the exhaust system, you must use original equipment parts (or their equivalent).

Scheme 4

1. Loosen intermediate pipe-to catalytic converter clamp. NOTE: Do not use petroleum-based lubricants when removing/installing muffler or exhaust pipe isolators as it may compromise the life of the part. A suitable substitute is a mixture of liquid dish soap and water.
2. Remove catalytic converter to exhaust manifold mounting nuts and gasket Discard gasket.
3. Remove I-Pipe/Muffler assembly insulators as necessary to slide catalytic converter out of I-Pipe/Muffler.

Note. When replacement is required on any component of the exhaust system, original equipment parts (or equivalent) must be used.

Scheme 5

Scheme 6

Scheme 7

Scheme 8

1. Remove engine trim cover (1).
2. Disconnect and isolate the negative battery cable.
3. Remove the turbocharger heat shield (2).
4. Remove the upstream temperature sensor from the catalytic converter.
5. Remove the catalytic converter to steady rest bracket bolt.
6. Loosen the turbocharger to catalytic converter band clamp (1).
7. Raise and support the vehicle. Refer to «HOISTING, STANDARD PROCEDURE»(ref-612692-S42044915732014043000000) .
8. Remove the belly pan from the vehicle. Refer to «BELLY PAN, REMOVAL»(ref-612698-S04899059452014043000000) .
9. Remove the right side half shaft and axle. Refer to «HALF SHAFT, FRONT - REMOVAL»(ref-612699-S21666616252014043000000) and «HALF SHAFT, RIGHT REAR - REMOVAL»(ref-612701-S18162721092014043000000) .
10. Remove the downstream temperature sensor (2) from the catalytic converter.
11. Remove the catalytic converter to diesel particulate filter (DPF) flange mounting nuts and gasket. Discard the gasket.
12. Remove the catalytic converter from underneath the vehicle.

Note. When replacement is required on any component of the exhaust system, original equipment parts (or equivalent) must be used.

A diesel particulate filter DPF is installed for exhaust gas after-treatment. The DPF is located downstream of the main oxidation catalyst. The DPF filters, stores and burns particulate matter (soot) that is generated during the combustion process. The soot is oxidized to carbon dioxide CO2 at exhaust temperatures over 600° C (1, 112° F).

The oxidation catalysts raise the exhaust gas temperatures to regenerate the DPF, which is passive regeneration. If the passive regeneration cannot keep up with the build up of soot in the DPF, the Powertrain Control Module (PCM) will actively regenerate the DPF to burn off the soot. Residue remains inside the DPF in the form of non burnable ash. Ash comes from the oils and other materials that are trapped in the oils and are present in the soot. Ash is not eliminated by the regeneration cycle. Excessive ash accumulation requires the replacement of the DPF. The DPF uses a silicon carbide wall-flow monolith with a platinum coating to trap particulates. The monolith contains a large number of square parallel channels, which run in the axial direction and are separated by thin porous walls. The channels are alternatively open at one end, but plugged at the other. The exhaust gases flow through the walls and escape through the pores in the wall material. Particulates, however, are too large to escape and are trapped in the monolith walls. The PCM starts the regeneration of the DPF if the soot load exceeds a performance map value. The PCM determines the load condition of the DPF based upon the exhaust gas pressure upstream and downstream of the DPF. A pressure differential sensor provides the pressure input to the PCM. During the regeneration process, the PCM raises the temperature in the DPF to burn off the soot accumulated. Under normal operation, the engine does not produce enough heat to oxidize the soot inside the DPF. This process requires temperatures above 550 °C (1, 022 °F). After regeneration, the PCM reads the actual pressure difference at the DPF and compares it with a reference value. From this comparison, the PCM determines the ash quantity inside the DPF.

Scheme 9

1. Disconnect the negative battery cable.
2. Raise and support the vehicle. Refer to «HOISTING, STANDARD PROCEDURE»(ref-612692-S42044915732014043000000) .
3. Remove the lower splash shield.
4. If equipped, remove the skid plate(s).
5. Saturate the Diesel Particulate Filter (DPF) (3) to catalytic converter flange bolts with heat valve lubricant. Allow 5 minutes for penetration.
6. If necessary, saturate the DPF (3) to muffler clamp with heat valve lubricant. Allow 5 minutes for penetration.
7. Remove the front differential pressure sensor tube (2).
8. Remove the rear differential pressure sensor tube (1).
9. Remove the DPF (3) from the front exhaust hanger.
10. Remove the DPF (3) to catalytic converter flange bolts.
11. Remove the DPF to muffler clamp.
12. Remove the DPF (3) from the vehicle.