System Check - Restricted Exhaust

Restricted Exhaust System Chart B-1:

DIAGNOSTIC NOTE
Proper diagnosis for a restricted exhaust system is essential before any components are replaced.

CHECK AT HEATED OR UNHEATED OXYGEN SENSORS

1. Carefully remove Oxygen Sensor.
2. Install exhaust backpressure tester (BT-8515 or 8603) or equivalent in place of Oxygen Sensor (see illustration).
3. After completing test described below, be sure to 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 three-way catalytic converter is suspected to be restricted and should be replaced using current recommended procedures.