Geely Emgrand X7. Manual part — 130

2.7.4.4 Middle Muffler Assembly

NL02-0011c

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2.7.4.5 Rear Muffler Assembly

NL02-0012c

520

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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