Exhaust System Backpressure

Exhaust system can be checked using a vacuum or pressure gauge. Remove O2 sensor or air injection check valve. Connect a 1-10 psi pressure gauge, and operate engine at 2500 RPM. If exhaust system backpressure is more than 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 it steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.