DIAGNOSIS AND TESTING
EXHAUST SYSTEM DIAGNOSIS
| CONDITION |
POSSIBLE CAUSES |
CORRECTION |
| EXCESSIVE EXHAUST NOISE (UNDER HOOD) |
1. Exhaust manifold cracked or broken. |
1. Replace manifold. |
| 2. Manifold to cylinder head leak. |
2. Tighten manifold and/or replace gasket. |
|
| 3. Exhaust flex joint to manifold leak. |
3. Tighten fasteners or replace gasket. |
|
| 4. Exhaust flex joint. |
4. Replace catalytic converter assembly. |
|
| 5. Pipe and shell noise from front exhaust pipe. |
5. Characteristic of single wall pipes. |
|
| EXCESSIVE EXHAUST NOISE |
1. Leaks at pipe joints. |
1. Tighten or replace clamps at leaking joints. |
| 2. Burned, blown, or rusted out exhaust pipe or muffler. |
2. Replace muffler or exhaust pipes. |
|
| 3. Restriction in muffler or tailpipe. |
3. Remove restriction, if possible or replace as necessary. |
|
| 4. Catalytic converter material in muffler. |
4. Replace muffler and converter assembly. Check fuel injection and ignition systems for proper operation. |
EXHAUST SYSTEM RESTRICTION CHECK
Exhaust system restriction can be checked by measuring back pressure using the scan tool and PEP module pressure tester.
WARNING: The normal operating temperature of the exhaust system is very high. Therefore, never work around or attempt to service any part of the exhaust system until it is cooled. Special care should be taken when working near the catalytic converter. The temperature of the converter rises to a high level after a short period of engine operation time.
NOTE: For Special Tool identification, (Refer to 11 - EXHAUST SYSTEM - SPECIAL TOOLS).
1. Disconnect and remove the upstream (before catalytic converter) oxygen sensor. (Refer to 14 - FUEL SYSTEM/FUEL INJECTION/O2 SENSOR - REMOVAL)
2. Install the Back Pressure Test Adaptor CH8519.
3. Connect the Pressure Transducer CH7063 to the back pressure fitting.
4. Following the PEP module instruction manual, connect all required cables to the scan tool and PEP module. Select the available menu options on the scan tool display screen for using the digital pressure gauge function.
5. Apply the park brake and start the engine.
6. With transmission in Park or Neutral, raise engine speed to 2000 RPM. Monitor the pressure readings on the scan tool. Back pressure should not exceed specified limit. Refer to specification in table below EXHAUST BACK PRESSURE LIMITS.
7. If pressure exceeds maximum limits, inspect exhaust system for restricted component. For further catalytic converter inspection procedures, (Refer to 11 - EXHAUST SYSTEM/CATALYTIC CONVERTER - INSPECTION). Replace component(s) as necessary.
| Exhaust Back Pressure Limit (Max) | |
| Vehicle in Park/Neutral (no load) @2000 RPM | 3.45 kPa (0.5 psi) |