Exhaust Emissions System - Catalytic Converters: Maintenance

There are several reasons why a catalytic converter may become ineffective or less effective than designed. These reasons include erosion by solid particles, breaks in the supports (strain on inlet or outlet flanges), clogging of the catalyst pores by use of leaded fuel and loss of effectiveness due to prolonged high temperature operation (long periods of hot idle or improperly tuned engine). A 4000 ppm (parts per million) emission level is acceptable (unless otherwise stated on emission label). If this level is not obtained on HC/CO meter, make necessary carburetor and/or ignition adjustments to obtain this reading.