Exhaust System Backpressure

Exhaust system backpressure can be checked with a vacuum gauge or a 0-5 psi pressure gauge. If a pressure gauge is used, remove O2 sensor. Connect gauge to O2 sensor port. Start and run engine at 2500 RPM. If backpressure is more than 2 psi, exhaust system is plugged.

If a vacuum gauge is used, connect it to intake manifold vacuum port. Start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge drops slowly after stabilizing, check exhaust system for a restriction.