Exhaust System Backpressure
WARNING: This page is about a different car, the 1993 Volkswagen Passat, 1993 Volkswagen Fox, 1993 Volkswagen EuroVan, 1993 Volkswagen Corrado, and 1993 Volkswagen Cabriolet. However, it is still accessible from the selected car via links, so may be relevant.
The exhaust system can be checked with a vacuum or pressure gauge. Remove O2 sensor or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge and operate engine at 2500 RPM. If exhaust system backpressure is greater 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 steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.