Mechanical Inspection - Exhaust System BACKPRESSURE
- Check exhaust system using a pressure or vacuum gauge. Using pressure gauge, remove O2 sensor or air injection check valve, which ever unit is ahead of catalytic converter and muffler(s). Connect a 1-10 psi pressure gauge and try to run engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4-2 psi (.12-.14 kg/cm2 ), 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 at idle. Open throttle part way and hold steady. If vacuum gauge reading slowly drops, exhaust system or catalytic converter is plugged.