a. A stoichiometric mixture is: (i) Comprised of 14.7 kg of air and 1 kg of fuel (ii) Always a lean

mixture; present if the engine is operated with an excess of air (iii) Comprised of 1 kg of air and 14.7 kg of fuel

b. What is the objective of using a lambda sensor?

(i) To trigger an alarm as soon as exhaust gasses enter the area occupied by the driver or

passengers

(ii) To measure the exhaust temperature and prevent overheating of the catalytic converter (iii) To convey important information to the engine control unit for the adjustment of the

fuelling system, this then provides the optimal air-fuel mixture

c. How does a ZrO2-based lambda sensor work?

(i) Its electrical resistance changes depending on the air-fuel mixture

(ii) The characteristic sensor voltage output is generated by the migration of oxygen ions

from the reference air in the direction of exhaust gas

(iii) The characteristic sensor voltage output is generated by the migration of oxygen ions

from the exhaust gas in the direction of the reference air

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d. How is the signal of a TiO2 lambda sensor produced?

(i) Oxygen ions migrate between Platinum electrodes on the TiO2 element depending on the

temperature

(ii) Depending on the oxygen content of the exhaust gas, released TiO2 molecules migrate

through the sensor element and generate a voltage

(iii) The TiO2 element changes its electrical resistance proportionally to the partial oxygen

pressure in the exhaust gas mixture

e. Which of the following statements apply to lambda sensors?

(i) If the sensor is defective, the vehicle will still pass an exhaust test

(ii) A sluggish defective sensor leads to increased fuel consumption and increased emission

of harmful exhaust gasses

(iii) If the sensor is defective, the air-fuel ration control cannot function and the vehicle

cannot start

f. The harmful exhaust emission consists primarily of: (i) NOx, HC, and CO gases

(ii) NOx, N2, and Noble gases

(iii) NOx, H2O, and CO gases

g. What are correct regarding lambda sensors?

(i) The ZrO2-based sensor does not commence operation until it reaches ~ 350 C

(ii) The value of the sensor is defined as a change in capacity between to two platinum

electrodes

(iii) In order for the catalyst to function optimally, the air-fuel ratio must be precisely

controlled

h. Which components do you not find in a ZrO2-based lambda sensor? (i) TiO2 element

(ii) ZrO2 element

(iii) Center electrode with Iridium tip

(iv) Integrated heating element

i. What are correct regarding lambda sensors?

(i) The installation position of the regulating sensor is usually before the catalytic converter (ii) The installation position of the diagnostic sensor is usually before the catalytic converter (iii) The installation position of the diagnostic sensor is usually after the catalytic converter (iv) The installation position of the regulating sensor is usually after the catalytic converter

j. What is correct regarding the air ratio?

(i) An air-fuel ratio corresponding to  = 1 has a stoichiometric mixture (ii) An air-fuel ratio corresponding to >1 has a rich mixture

(iii) An air-fuel ratio corresponding to <1 has a lean mixture 

 

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