Catalytic Converter: Testing and Inspection

Proper diagnosis for a restricted exhaust system is essential before any components are replaced. The following procedure(s) may be used for diagnosis:

Exhaust System Test at A.I.R. Pipe:

CHECK AT A.I.R. PIPE:

1. Remove the rubber hose at the exhaust manifold A.I.R. pipe check valve. Remove check valve.
2. Connect a fuel pump pressure gauge to a hose and nipple from a Propane Enrichment Device.
3. Insert the nipple into the exhaust manifold A.I.R. pipe.

Exhaust System Test at Oxygen Sensor:

CHECK AT 02 SENSOR:

1. Carefully remove O2 sensor.
2. Install Exhaust Backpressure Tester in place of 02 sensor.
3. After completing the diagnosis described below, be sure to coat threads of 02 sensor with anti-seize compound prior to re-installation.




DIAGNOSIS:

1. With the engine idling at normal operating temperature, observe the exhaust system backpressure reading on the gauge. The reading should not exceed 1.25 psi or 8.6 kPa. Increase engine speed to 2000 rpm and observe gauge. The reading should not exceed 3 psi or 20.7 kPa.

2. If the backpressure exceeds the given specifications, a restricted exhaust system is indicated.

3. Inspect the entire exhaust system for a collapsed pipe, heat distress, or possible internal muffler failure.

4. If there are no obvious reasons for the excessive backpressure, a restricted catalytic converter should be suspected, and replaced.