Perform Vacuum Test - Exhaust Disconnected

^ Turn engine OFF.

^ Disconnect exhaust system at exhaust manifold.

^ Repeat vacuum test. Perform Vacuum Test

^ Did manifold vacuum reach above 406.4 mm-Hg (16 in-Hg)?

YES -- Proceed to Perform Vacuum Test - TWC Converter On/Muffler Off. Perform Vacuum Test - TWC Converter On/Muffler Off

NO -- Proceed to Check Exhaust Manifold Restriction. Check Exhaust Manifold Restriction