3-14
Vehicle Testing
Pre-test Inspection
During emission troubleshooting, the catalytic converter should be
the last item to be tested and/or repaired. Perform the following
inspection before starting the catalytic converter test.
X
Make sure all diagnostic trouble codes are repaired.
X
Make sure all engine controls and emission controls are
operating correctly. To verify correct operation of the emission
control system, check O
2
sensor for proper operation.
X
Always comply with the governing emission control standards
and regulations in your locality when testing exhaust emission
pollutant levels.
X
Make sure engine systems are within specifications, especially
timing.
X
Replace catalytic converters with severe rust or case damage.
X
The catalytic converter should not rattle when given a quick rap.
A rattle may indicate the substrate has broken. If the substrate is
broken the catalytic converter will soon fail and may plug the
exhaust.
X
Always follow vehicle manufacturer specifications when working
on emission control devices to comply with anti-tampering laws.
X
Do not test exhaust emissions on vehicles that are smoking
excessively or are in obvious need of engine repair. Testing
exhaust gas under such conditions may contaminate the
sampling system and cause inaccurate readings.
X
Repair leaks in exhaust system prior to testing. Leaks adversely
affect analyzer readings.
Test Preparation
Before performing tests in this manual be sure that:
•
Analyzer is on, warmed up and calibrated,
•
Leads and probes are connected to vehicle in standard
configuration,
•
Vehicle parking brake is applied.
•
Gear selector is in:
— Neutral, if equipped with a manual transmission, or
— Park, if equipped with an automatic transmission.
•
Drive wheels are blocked,
•
Parking brake is set, and
— If vehicle equipped with automatic parking brake release,
disable release mechanism.
•
All testing tips and safety requirements are observed.
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