2.7.4.4 Middle Muffler Assembly 

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2.7.4.5 Rear Muffler Assembly 

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2.7.5 Diagnostic message and steps 

2.7.5.1 Diagnosis descriptions 

Refer to 2.7.2 Description and Operation, get familiar with the system functions and operation 
before starting system diagnosis, so that it will help to determine the correct diagnostic steps, more 
importantly, it will also help to determine whether the situation described by the customer is 
normal. 

2.7.5.2 Visual inspection 

z  Inspect installed after market equipment that may affect the operation of the exhaust system. 

z  Inspect easy to access system components to identify whether there are significant blockages 

or leakage. 

z  Inspect whether the color of the exhaust gas is normal. 

2.7.5.3 Exhaust System Blockage 

When the engine loses power, fuel economy becomes worse or acceleration performance is poor, 
inspect whether there is ""exhaust system blockage"" fault, use the exhaust back-pressure to 
monitor whether the back-pressure is more than 50 kPa to confirm the fault. The fault may be 
caused by following reasons: 

z  Exhaust pipe is damaged. 

z  There are debris in exhaust pipes. 

z  Muffler or resonator internal faults. 

z  Exhaust pipe internal corrosion blocks the rear exhaust port. 

2.7.5.4 Exhaust System Leakage 

If the engine has "hiss" or a burst sound when running, inspect whether there is "Exhaust System 
Leakage" fault, as shown in the following table: 

Misalignment or incorrect 
installation of exhaust system 
components 

z  Position and tighten the exhaust system components to the 

specified torque. Refer to 2.7.1.1 Fastener Specification 

z  Make sure that the exhaust pipe hook is in the right place 

and is not loose. 

Exhaust leak at the following 
connections: 

z  Exhaust manifold and 

front exhaust pipe 
assembly 

z  Flange 

Tighten the related components to the specified torque. Refer to 
2.7.1.1 Fastener Specification 

Seal or Gasket Leak: 

z  Exhaust Manifold and 

Cylinder Hood 

z  Exhaust manifold and 

front exhaust device 
assembly 

z  Three-Way Catalytic 

Replace leaking seals or linings. 

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Converter and middle 
Muffler 

z  Middle Muffler and Rear 

Muffler Replace the 
leaking seals or gasket. 

Flange Irregular Joints 

If necessary, repair or replace the relevant components. 

Exhaust Manifold Cracked or 
Broken 

Replace the exhaust manifold. Refer to 2.7.6.1 Replacement of 
Exhaust Manifold. 

Exhaust system components 
welded joints leakage 

Replace the leaking components. 

2.7.5.5 Exhaust System Noise 

When the engine is running, exhaust has noise or unusual sound. Inspect whether there is "Exhaust 
System Blockage" fault, as shown in the following table: 

Cracking or hissing 

Exhaust System Leakage Refer to 2.7.5.3 Exhaust System Blockage. 

Exhaust sound too 
large 

1.  Compare with a vehicle known in good conditions. 

2.  Inspect the muffler for damage or malfunction. Replace the faulty 

muffler. 

3.  Refer to 2.7.6.4 Replacement of Middle Muffler and 2.7.6.5 

Replacement of Rear Muffler. 

External Noise or 
Vibration Noise 

1.  Inspect whether the hook is bent or loose or whether shrouds 

fasteners are loose. 

2.  Inspect whether the exhaust pipe is interfered. 

Internal Noise 

1.  With a rubber hammer knock these components to confirm the noise.

2.  Replace the faulty three-way catalytic converter or muffler. Refer to 

2.7.6.3 Replacement of Three-way Catalytic Converter Assembly or 
2.7.6.4 Replacement of Middle Muffler or 2.7.6.5 Replacement of 
Rear Muffler. 

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