Conditioning For Sensor Testing
Perform the operation with the engine speeds and time durations described below prior to checking the waveforms of the A/F and HO2 sensors. This is performed in order to heat the sensors sufficiently to obtain the appropriate inspection results.
- (a) Put the engine in inspection mode. Refer to INSPECTION MODE PROCEDURE and connect the Techstream to the DLC3.
- (b) Warm it up with all the accessories switched off, until the engine coolant temperature stabilizes.
- (c) Run the engine at an engine speed of between 2000 rpm and 2500 rpm for at least 3 minutes.
- (d) While running the engine at 2500 rpm and 1500 rpm alternating at 2 second intervals, check the waveforms of the A/F and HO2 sensors using the Techstream.
HINT:
- If either voltage output of the Air-Fuel Ratio (A/F) or Heated Oxygen (HO2) sensor does not fluctuate, or there is a noise in the waveform of either sensor the sensor may be malfunctioning.
- If the voltage outputs of both the sensors remain lean or rich, the air-fuel ratio may be extremely lean or rich. In such cases, perform the following Control the Injection Volume for A/F Sensor using the Techstream.
- If the Three-Way Catalytic Converter (TWC) has deteriorated, the HO2 sensor (located behind the TWC) voltage output fluctuates up and down frequently, even under normal driving conditions (active air-fuel ratio control is not performed).