Example of an Emissions Test
CO and hydrocarbon tailpipe
emissions from a test vehicle
during a test cycle. Also shown
is the catalyst temperature and
speed during the cycle.
Catalyst mounted 1.2 m from
As can be seen, the principal CO
and hydrocarbon emissions
occur catalyst warmup. Data for
NO production is not reported.
When hot, the catalyst is very
effective. In practice, one can expect
between 60 and 90% of the engine CO and hydrocarbon emissions, as measured over the whole test cycle, to be removed by the catalyst after 50,000 miles of use.