EX2 - Vacuum Test, Exhaust Disconnected

^ Turn the engine off.

^ Disconnect the exhaust system at the exhaust manifold.

^ Repeat Test EX1. Is the manifold vacuum above 508mm (20 in) of mercury?

YES -- GO to Ex3. EX3 - Vacuum Test, Converter On, Muffler Off

NO -- GO to EX4. EX4 - Exhaust Manifold Restriction