Exhaust Emission Control System - Honda CRF1000 Shop Manual

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GENERAL INFORMATION

EXHAUST EMISSION CONTROL SYSTEM

The exhaust emission control system is composed of a secondary air injection system, a three-way catalytic converter and PGM-FI
system.
SECONDARY AIR SUPPLY SYSTEM
The secondary air supply system introduces filtered air into the exhaust gases in the exhaust port. Fresh air is drawn into the
exhaust port by the function of the PAIR (Pulse Secondary Air Injection) control solenoid valve.
This charge of fresh air promotes burning of the unburned exhaust gases and changes a considerable amount of hydrocarbons and
carbon monoxide into relatively harmless carbon dioxide and water vapor.
The reed valve prevents reverse air flow through the system. The PAIR control solenoid valve is operated by the solenoid valve.
The solenoid valve is controlled by the ECM/PCM, and the fresh air passage is opened/closed according the running condition
(ECT/IAT/TP/MAP sensor and engine revolution).
No adjustments to the secondary air supply system should be made, although periodic inspection of the components is
recommended.
PAIR CONTROL
SOLENOID VALVE
PAIR REED VALVE
EXHAUST PORT
Three-way catalytic converter
This motorcycle is also equipped with three-way catalytic converter, and two heated oxygen sensors.
The three-way catalytic converter is in the exhaust system. Through chemical reactions, they convert HC, CO, and NOx in the
engine's exhaust to carbon dioxide (CO
No adjustment to these systems should be made although periodic inspection of the components is recommended.
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FRESH AIR
EXHAUST GAS
), dinitrogen (N ), and water vapor.
2 2
AIR CLEANER HOUSING
THROTTLE BODY