System Description: Description

The air-fuel mixture ratio control is performed when the following conditions are satisfied.

• During the engine is running
• Engine coolant temperature: Changes according to driving condition.
• Operating temperature of A/F sensor must be satisfied.
• The deceleration fuel shut-off function must be deactivated.

ECM performs control for satisfying the theoretical air-fuel ratio as much as possible to allow the catalyst to effectively purge exhaust gas.

ECM controls the air-fuel mixture ratio corrections according to the following sensors.

• Engine coolant temperature sensor
• Pressure sensor downstream of throttle valve (Engine load)
• Air fuel ratio (A/F) sensor
• Heated oxygen sensor

Effective purge of exhaust gas in the three way catalyst 

Courtesy of NISSAN NORTH AMERICA, INC.

The air-fuel mixture ratio control has functions as follows.

• Air-fuel mixture ratio corrections closed-loop control
• A/F sensor control
• Sensor heater control
• Air-fuel mixture ratio corrections adjustment control
• Catalyst monitoring function