To begin, an internal combustion engine creates heat energy by igniting a mixture of gasoline and atmospheric oxygen with a high-voltage spark.
Andrew Markel shows how an EVAP code and a catalyst efficiency code are both related to weak motor mounts. Sponsored by Auto Value and Bumper to Bumper.
Engine management systems compensate for changes in engine speed, loads and temperatures by adjusting the amount of fuel injected, spark advance/retard and even when the intake and exhaust valves open. These adjustments can only do so much. Tailpipe emissions are cut further by exhaust gas recirculation (EGR) and secondary air injection systems. The last line
Although construction can vary according to engine application, the common three-way catalytic converter contains a reduction and oxidation stage. To create maximum surface area, each stage is generally a ceramic or stainless steel honeycomb substrate covered with a rough silica and alumina wash coat. Both stages of the converter are coated with precious metal catalysts
The ASE X1 Certification Test has a section (8 questions) focused on emissions system diagnosis. For that section, among other things, you will need to: • Identify failed catalytic converter(s); determine cause of failure; determine needed repair. • Identify failed oxygen sensor(s) (O2S/HO2S) component(s) and circuitry; determine cause of failure; determine needed repair. • Inspect