Oxygen Sensor Heating
Oxygen sensor heating is activated by the ECU when the following conditions are met:
- – intake pressure is below a certain threshold depending on engine speed;
- – speed below 135 km/h;
- – after the engine has been running for a certain period of time, determined depending on the TDC of the engine cylinders (if the accelerator pedal is not in the idle position) and the coolant temperature.
Oxygen sensor heating is deactivated when the following conditions are met:
- – vehicle speed above 140 km/h (reference value);
- – high engine load.
Working fluid composition adjustment
The value of parameter PR 138 "AIR FLUID-MIXTURE CORRECTION VALUE" read on the diagnostic tool is an average value entered by the ECU depending on the air-fuel mixture information transmitted by the oxygen sensor installed before the catalytic converter (the oxygen sensor analyzes the oxygen content in the exhaust gases).
Correction value for the midpoint of 50% and for the extreme positions of 0 and 100%:
- – a value below 50% requests a leaner mixture;
- – a value above 50% requests a richer mixture.
Start of air-fuel mixture control
1. Closed-loop control phase.
Fuel mixture regulation begins some time after the engine is started, if the coolant temperature is above 10°C (vehicles with a manual transmission) and 25°C (vehicles with an automatic transmission).
2. Open-loop control phase.
When regulating the fuel mixture, the ECU does not take into account the sensor signal voltage in the following cases:
- – when the accelerator pedal is fully depressed;
- – under significant loads and high crankshaft speed;
- – when decelerating, if there is information that the accelerator pedal has been released;
- – if the oxygen sensor fails.