System Check - Restricted Exhaust

(Figure 1) Back Pressure Gauge Hook-up:

CHECK AT HEATED OXYGEN SENSOR (HO2S) SENSOR
1. Carefully remove HO2S Sensor.
2. Install exhaust backpressure tester kit J 35314-A in place of HO2S (Figure 1).
3. After completing test described below, be sure to coat threads of HO2S with anti-seize compound Part Number 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 gauge. Reading should not exceed 8.6 kPa (1.25 psi).
2. Increase engine speed to 2000 RPM and observe gauge. 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.