Component Tests and General Diagnostics

EXHAUST SYSTEM RESTRICTION CHECK

Exhaust system restriction can be checked by measuring back pressure using the DRBIII 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 Tools and Equipment.

1. Disconnect and remove the upstream (before catalytic converter) oxygen sensor.
2. Install the Exhaust Back Pressure Fitting Adapter CH8519.
3. Connect the Low Pressure Sensor (15 psi) CH7063 to the back pressure fitting.
4. Following the PEP module instruction manual, connect all required cables to the DRBIII and PEP module. Select the available menu options on the DRBIII 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 DRBIII. 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. Replace component(s) as necessary.

EXHAUST BACK PRESSURE LIMITS:

INSPECTION
Inspect the exhaust pipes, catalytic converters, muffler, and resonators for cracked joints, broken welds and corrosion damage that would result in a leaking exhaust system. Inspect the clamps, support brackets, and insulators for cracks and corrosion damage.

NOTE: Slip joint band clamps are spot welded to exhaust system. If a band clamp must be replaced, the spot weld must be ground off.