Exhaust System Backpressure
WARNING: This page is about a different car, the 1995 Dodge Ram Wagon, 1995 Dodge Ram Van, 1995 Dodge Pickup, and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Check exhaust system using a vacuum gauge or pressure gauge. Remove oxygen sensor or air injection check valve (if equipped). Connect a 1 - 5 psi (6.9 - 34.5 kPa) pressure gauge, and run engine at 2500 RPM. If exhaust system backpressure is greater than 1.75 - 2 psi (12.0 - 13.8 kPa), exhaust system or catalytic converter is plugged.
If using a vacuum gauge, 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.