B Charts

Exhaust Backpressure Test Gage Hook-up:

CHECK AT OXYGEN SENSOR
1. Carefully remove heated or unheated oxygen sensor.
2. Install exhaust backpressure tester (BT-8515 or BT-8603) or equivalent in place of heated oxygen sensor (see image).
3. After completing test described below, coat threads of the 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.

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