General information
On models with a 2.7 liter engine, a titanium oxygen sensor is installed (TiO2).
The oxygen sensor determines the concentration of oxygen in the exhaust gases and accordingly changes the voltage of the signal that enters the electronic engine control unit. If the composition of the air-fuel mixture is richer than the stoichiometric ratio (those. if the oxygen concentration in the exhaust gases is low), then the sensor signal voltage is approximately 0 V.
If the air-fuel mixture is leaner than the stoichiometric ratio (those. if the concentration of oxygen in the exhaust gases is high), then the sensor signal voltage is approximately 5 V. Based on this signal, the engine control unit regulates the fuel supply to the cylinders so that the composition of the air-fuel mixture is as close to the stoichiometric ratio as possible.
The oxygen sensor is equipped with a heater, which ensures stable operation of the sensor in all modes.
Note: the pictures below show one of the options for the location of the front and rear oxygen sensors (two sensors before the pre-catalytic converter and two after it), but there is another option with one front and rear oxygen sensors.
front sensor (left cylinder head). | rear sensors. |
Troubleshooting Guide
1. If the oxygen sensor is defective, then the exhaust gases will contain an increased content of toxic substances.
2. If the oxygen sensor signal (output voltage) differs from the nominal value, after the test showed that the sensor is working, then the cause of the malfunction in the components of the air-fuel mixture control system:
- A) Injector failure.
- b) Air enters the intake manifold through a damaged gasket.
- V) Malfunction of the air flow sensor, intake manifold air temperature sensor and coolant temperature sensor.
Testing with a tester
1. Perform an oxygen sensor test when the engine is: warm (the air-fuel mixture will be leaner when the engine speed is reduced, and enriched when the accelerator pedal is pressed).
- A) Measure the nominal value at hard deceleration from 4000 rpm.
- Rated value: 300-900mV
- b) Measure the nominal value with a rapid increase in the speed of the crankshaft.
- Rated value: 4000-4800mV
2. Perform an oxygen sensor test when the engine is: warm (using signals from the oxygen sensor, check the composition of the air-fuel mixture and the quality of engine control (electronic control unit)).
- A) Measure the nominal value at idle.
- Rated value: 300-4800mV
- b) Measure the nominal value at 2000 rpm.
- Rated value: 300-4800mV
Checking with a voltmeter
1. Disconnect the oxygen sensor connector and measure the resistance between the terminals "3" And "4" sensor.
Note: before checking, warm up the engine so that the coolant temperature reaches 80-95°C.
- A) Check that the resistance is 4.0-5.2 ohms at 23°C.
- b) Check that the resistance is 8.2-11.1 ohms at 400°C.
2. Connect the power (battery voltage) straight to the conclusion "3" And "4" sensor.
Note: Be careful when performing this operation. Incorrect power connections or shorting the leads will damage the oxygen sensor.
3. Connect a digital voltmeter between the leads "1" And "2" sensor.
4. Periodically pressing the accelerator pedal, measure the output voltage of the oxygen sensor.
- Oxygen sensor output voltage (when pressing the accelerator pedal): 4000-5000mV
Note: The air/fuel mixture is slightly richer as the engine speed increases (overclocking).
5. If the sensor signal is not correct, then the oxygen sensor may be defective.
Torque:
- Oxygen sensor: 40-50 Nm
- Oxygen sensor wiring retainer bolt: 8-12 Nm