Honda HR-V: PGM-FI System Description - A/F Sensor/HO2S Feedback Air/Fuel Ratio Control (KA/KC)

Air-fuel ratio control is part of fuel injection control and comprises the steps of:

• Calculating basic injection amount from intake airflow amount and engine speed
• Calculating air-fuel ratio correction value from the oxygen density in the exhaust gas and reflecting the calculated values to the injection amount

Air-fuel ratio control stops feedback under the following conditions in order to maintain operational performance and catalytic protection.

• When starting the engine or during fuel increase after the engine is started
• While the engine coolant is cold
• During fuel increase under high load
• During fuel increase at high engine speed
• During fuel cut-off at deceleration

Air Fuel Ratio (A/F) Sensor (Sensor 1)

The air fuel ratio (A/F) sensor (sensor 1) is installed on the warm up three way catalytic converter (WU-TWC).

Air fuel ratio control performs fuel injection control based on the oxygen density detected in exhaust gas in order to bring the intake mixture in the vicinity of a target air-fuel ratio. This high-precision air fuel ratio control is realized by detecting a correction value with a A/F sensor (sensor 1) and then applying further correction with a secondary heated oxygen sensor (secondary HO2S) (sensor 2).The sensor element and the heater inside the A/F sensor (sensor 1) have a layered construction of a plate-shaped zirconia element which inside and outside are coated with platinum and a built-in platinum heater. A ceramic coating diffusion layer on the platinum electrode on the outside of the element creates an atmospheric chamber between the platinum electrode inside the element and the heater.

Secondary HO2S (Sensor 2)

The secondary heated oxygen sensor (secondary HO2S) (sensor 2) is installed under-floor three way catalytic converter (under-floor TWC), and it detects the oxygen density in the exhaust gas passing through the catalyst and outputs it to the powertrain control module (PCM) to enable the high-precision air fuel ratio control, which cannot be realized only with an A/F sensor (sensor 1). Inside the secondary HO2S (sensor 2) is a test tube shaped zirconia element which inside and outside surfaces are coated with platinum. The inside surface is exposed to the atmosphere, while the outside surface is within the exhaust gas. A ceramic heater is equipped inside the element in order to shorten sensor reaction time and to enable output that is constantly stable.

PGM-FI SYSTEM DESCRIPTION - FUEL CUT-OFF CONTROL

Recovery engine speed from fuel cut-off during deceleration

After warming up, during deceleration with the throttle valve slightly opened from the fully closed position, the powertrain control module (PCM) stops the fuel injection when the engine speed is over the specified value or more to improve fuel efficiency.

Fuel cut-off at high engine speed

To prevent the engine from damage, the PCM stops fuel injection when the engine speed is in the limited area (red zone). PCM stops fuel injection while vehicle is driven and while at a stop. Fuel cut engine speed is lower when stopped compared to when driven.

READ NEXT: