Perform Vacuum Test - TWC Converter On/Muffler Off

^ Turn engine Off.

^ Reconnect the exhaust system at the exhaust manifold.

^ Disconnect the muffler.

^ Repeat vacuum test. Perform Vacuum Test

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

YES -- Replace the muffler.

NO -- Replace the three way catalytic converter and inspect the muffler to be sure converter debris has not entered the muffler. Go to Rerun Exhaust Emission Test. Rerun Exhaust Emission Test