Exhaust System Backpressure
WARNING: This page is about a different car, the 2003 Volkswagen EuroVan, 2002 Volkswagen EuroVan, 2001 Volkswagen EuroVan, 2000 Volkswagen EuroVan, and 1999 Volkswagen EuroVan. However, it is still accessible from the selected car via links, so may be relevant.
A restricted exhaust system can be checked with a vacuum or pressure gauge. Remove heated oxygen 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 3 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.