B Charts

RESTRICTED EXHAUST SYSTEM CHECK
1. Carefully remove Heated Oxygen Sensor (HO2S) from exhaust manifold.
2. Install exhaust backpressure tester (BT-8515 or BT-8603) or equivalent in place of HO2S (see image).
3. After completing test described below, be sure to coat threads of HO2S with anti-seize compound P/N 5613695 or equivalent prior to re-installation.

DIAGNOSIS
1. With the engine at normal operating temperature and running at 2500 RPM, observe the exhaust system backpressure reading on the gauge.
2. If the backpressure exceeds 8.62 kPa (1.25 psi), 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 using current recommended procedures.