Volvo Workshop Manuals
940 L4-2.3L SOHC VIN 88 B230F (1992)
Engine, Cooling and Exhaust > Exhaust System > Catalytic Converter > Component Information > Technical Service Bulletins > Page 4083
Catalytic Converter: Testing and Inspection
Fig. 62a CATALYTIC CONVERTER TESTING
The efficiency of the catalytic converter can be checked by measuring and comparing the CO content before and after the converter. The CO
Inspect Catalytic convertor for external cracks.
Remove the catalytic converter from the vehicle. With either opening toward a light source, inspect the ceramic insert from both sides. If the
If excessive exhaust back pressure is suspected, eliminate the exhaust system as a cause. If exhaust back pressure remains excessive with all
If the exhaust system rattles during engine operation, check the catalytic convertor for a loose core. With the vehicle raised (for access), tap the
If all other emission systems are functioning correctly, but vehicle still has excessive tailpipe emissions, the catalytic convertor core may by
Warm the engine to normal operating temperature.
Run the engine at 2500 RPM for 30 seconds.
Using a pyrometer, measure the exhaust pipe temperature before and after the catalytic convertor.
Exhaust pipe temperature should be at least:
100° F hotter at the convertor outlet than at the inlet.
If catalytic convertor has little or no effect on exhaust temperature, the core may be contaminated.
If exhaust temperature exceeds 450° F, the engine may be running too lean. Repair the lean running condition and recheck exhaust
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