Hydrocarbon (HC) is basically raw fuel, otherwise known as gasoline. The
main reason vehicles fail for high HC is defective spark delivery.
Sparkplugs and spark wires are constantly exposed to high temperatures and
high voltages. You must ensure your engine's ignition system is functioning
properly, by inspecting all the sparkplugs and their wires. If any of the
plugs look worn out or have excessive carbon build-up replace them
immediately. You may use any brand of product designed to work in your
vehicle. The distributor cap should also be inspected for cracks or
excessive carbon deposits. If it appears that the cap may be faulty, you
will need to replace it. More then likely you will see an instant
performance increase once these corrections are made.
The repairs/modifications you've mention can improve the chances of your
Acura Legend passing the smog test... The only way is to take the next test.
Good luck.
