A/F Control
HINT:
Hand-held tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.
The following instructions describe how to conduct the A/F CONTROL operation using a hand-held tester.
- Connect a hand-held tester to the DLC3.
- Start the engine and turn the tester ON.
- Warm up the engine at an engine speed of 2,500 RPM for approximately 90 seconds.
- On the tester, select the following menu items: DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/A/F CONTROL.
- Perform the A/F CONTROL operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
- Monitor the voltage outputs of the A/F and HO2 sensors (AFS B1S1 and OS2 B1S2) displayed on the tester.
HINT:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.
- Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
Standard:
SENSOR VOLTAGE SPECIFICATIONS
| Tester Display (Sensor) | Injection Volumes | Status | Voltages |
|---|---|---|---|
| AFS B1S1 (A/F) | +25 % | Rich | Less than 3.0 |
| AFS B1S1 (A/F) | -12.5% | Lean | More than 3.35 |
| O2S B1S2 (H02) | +25% | Rich | More than 0.55 |
| O2S B1S2 (HO2) | -12.5% | Lean | Less than 0.4 |
NOTE:
The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.
- Following the A/F CONTROL procedure enables technicians to check and graph the voltage outputs of both the A/F and HO2 sensors.
- To display the graph, select the following menu items on the tester: DIAGNOSIS/ENHANCED OBD II/ACTIVE TEST/A/F CONTROL/USER DATA/AFS B1S1 and O2S B1S2, and press the YES button and then the ENTER button followed by the F4 button.