On Tue, 15 Apr 2003, John Connolly wrote:

> putting an "air pump" on an engine to pump fresh air into the exhaust system
> (which dilutes the pollutants with "clean" stuff, bringing the ratios down)
> is/was a common and legal method of making a car "cleaner".

Actually, the purpose of the air pump wasn't dilution, it was to add
oxygen to the exhaust stream so any unburned fuel would "afterburn" in the
exhaust system.

David Brodbeck, N8SRE
'82 Diesel Westfalia
'94 Honda Civic Si