HF12 - Check Vacuum Without Muffler/Tailpipe

*** THIS ARTICLE REFLECTS CHANGES MADE BY TSB # 9326B7, December 1993

- Key Off.

- Disconnect muffler/tail-pipe assembly located after the catalytic converter.

- Repeat the vacuum measurement found in test step HF10.

- Did the vacuum needle QUICKLY rise above 16 inches Hg with the engine rpm at 2000?

YES -- There is a restriction in the muffler/tail-pipe assembly. REPLACE the muffler/tail-pipe assembly. REMOVE the vacuum gauge and tachometer. COMPLETE the PCM reset to clear all DTCs. Clearing Diagnostic Trouble Codes

Rerun quick test. Diagnostic Subroutines (DSR) - Extracting Codes

NO -- There is a restriction in the catalytic converter. REMOVE the vacuum gauge and tachometer. REPLACE the catalytic converter and INSPECT the muffler to be certain converter debris has not entered. RECONNECT muffler/tail-pipe assembly. COMPLETE the PCM reset to clear all DTCs. Clearing Diagnostic Trouble Codes

Rerun quick test. Diagnostic Subroutines (DSR) - Extracting Codes