System Check - Restricted Exhaust

Exhaust Backpressure Gauge With AIR Pipe Adapter:

Exhaust Backpressure Gauge With O2S Adapter:

DIAGNOSING EXHAUST RESTRICTIONS
Proper diagnosis for a restricted exhaust system is essential before any components are replaced. Either of the following procedures may be used for diagnosis, depending upon engine or available tool.

CHECKING BACKPRESSURE AT AIR PIPE
1. Remove the rubber hose at the exhaust manifold Air Injection Reaction (AIR) pipe check valve. Remove check valve.

2. Connect exhaust backpressure kit (with air adapter) J35314-A.

3. Insert the adapter into the exhaust manifold AIR pipe.

CHECKING BACKPRESSURE AT OXYGEN SENSOR
1. Carefully remove oxygen sensor.

2. Install exhaust backpressure gage J35314-A in place of oxygen sensor (refer to accompanying image).

3. After completing test described below, coat threads of oxygen sensor with anti-seize compound P/N 5613695 or equivalent prior to re-installation.

DIAGNOSIS
1. With the engine idling at normal operating temperature, observe the exhaust system backpressure reading on the gage. Reading should not exceed 8.6 kPa (1.25 psi).

2. Increase engine speed to 2000 RPM and observe gage. Reading should not exceed 20.7 kPa (3 psi).

3. If the backpressure at either speed exceeds specification, a restricted exhaust system is indicated.

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

5. If there are no obvious reasons for the excessive backpressure, the catalytic converter is suspected to be restricted and should be replaced using current recommended procedures.