Honda 2005 VTX1800C Owner's Manual page 216

Exhaust Emission Control System
California only:
The exhaust emission control system
includes two three-way catalytic
converters, two heated oxygen sensors, a
secondary air supply system, and a PGM-
FI system.
49-state & Canada:
The exhaust emission control system
includes two oxidation catalytic converters,
a secondary air supply system, and a
PGM-FI system.
Both systems:
No adjustment to these systems should be
made although periodic inspection of all
components is recommended.
Emission Control Systems
PGM-FI System
The PGM-FI system uses sequential
multiport fuel injection. It has four
subsystems: Air Intake, Engine Control,
Fuel Control, and Exhaust Control.
The Engine Control Module (ECM) uses
various sensors to determine how much air
is going into the engine. It then controls
how much fuel to inject under all
operating conditions.
Ignition Timing Control System
The system constantly adjusts the ignition
timing, reducing the amount of HC, CO
and NOx produced.
Technical Information
207