Exhaust System Backpressure
The exhaust system can be checked with a vacuum or pressure gauge. Remove Heated Oxygen Sensor (HO2S). Connect a 0-5 psi pressure gauge and run engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4 - 2 psi, exhaust system or catalytic converter is plugged.
If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.
WARNING:
Use caution when engine is operating. DO NOT
stand in a direct line with fan. Keep hands and clothing away from pulleys, belts or fan. DO NOT
wear loose clothing.