NTTA questions - Exhaust Emissions

Sample exhaust emissions questions

When a petrol engine is running rich the exhaust gas hydrocarbon (HC) will be?
A = higher than it should be
B = lower than it should be
C = the same as when the engine is running weak
D = the same as the exhaust gas carbon monoxide content

Petrol is mainly composed of?
A = nitrogen and oxygen
B = oxygen and hydrogen
C = oxygen and carbon
D = carbon and hydrogen

If a carburetor petrol engine develops a leak in the inlet manifold it will?
A = run weaker
B = run richer
C = cause excessive exhaust smoke
D = cause none of the above

Which one of the following is the most UNLIKELY to be found in the exhaust from a petrol engine?
A = carbon
B = nitrogen
C = water
D = helium

Which one of the following is true about a petrol engine exhaust catalytic converter?
A = it converts carbon monoxide (co) to carbon dioxide (co2)
B = it converts carbon dioxide (co2) to carbon monoxide (co)
C = it converts hydrogen (X) to carbon dioxide (co2)
D = its converts hydrogen (X) to carbon monoxide (co)

A carburetor petrol engine with a seal crank case system that becomes blocked is likely to?
A = run weaker
B = run richer
C = run differently
D = run hotter

Which one of the following does NOT effect the amount of carbon monoxide in the exhaust emitted from a?
A = ignition timing
B = valve timing
C = Air cleaner condition
D = exhaust silencer condition

Which one of the following would cause a VERY HIGH o2 (oxygen) content (over 10%) in the exhaust emissions reading from the tail pipe of a petrol engine?
A = a weak mixture
B = incorrect ignition timing
C = an inlet manifold leak
D = a serious leak in the exhaust system

What does the petrol engine “Lambda sensor” do?
A = measure o2 (oxygen) in the exhaust gas before it reaches a catalytic converter
B = allow air into the inlet manifold to stop ‘running on’
C = pre-heat to assist with cold starting.
D = monitor ignition timing

Which one of the following is typical compression for a 1990 manufactured car with a high speed indirect injection DIESEL engine?
A = 35.0
B = 20 : 0
C = 10.0
D = 7.0

Which one of the following is not required on a diesel engine?
A = a governor
B = a fuel injector
C = a float chamber
D = an inlet manifold

To measure the idle engine speed exhaust emissions from a petrol engine car with automatic transmission it should be done when?
A = the gear box selector is set in the ‘park’ position
B = the gear box selector is set in the ‘drive position and the brakes are applied
C = the gear box selector is set in the ‘drive’ position and the road wheels are chocked
D = the engine is cold.


The color of the exhaust gas emitted from a petrol engine that is running very rich is likely to be?
A = black
B = white
C = dark blue
D = light blue

49. A 4 cylinder petrol engine has an exhaust gas hydrocarbon content of 600 ppm (parts per million). What is the hydrocarbon content likely to be when a plug lead is removed?
A = over 900 ppm
B = 600 ppm
C = 500 ppm
D = under 400 ppm

50. The CO (carbon monoxide) content of the exhaust gas emitted from a properly maintained non-cat 4 cylinder petrol engine in good condition is most likely to be?
A = 3.0%
B = 9.0%
C = 12.0%
D = 15.0%

51. Which one of the following petrol / air mixtures is closest to the theoretical best for the most complete combustion in a petrol engine?
A = 20 air units to 1 petrol unit
B = 15 air units to 1 petrol unit
C = 20 petrol units to 1 air unit
D = 15 petrol units to 1 air unit

52. Which one of the following fuels should be used when there is a catalytic converter in the exhaust system?
A = 100 octane petrol having 1.4% Tetraethyl-lead
B = 92 octane petrol having 0.4% Tetraethyl-lead
C = 92 octane petrol without any Tetraethyl-lead
D = a blend of 85 octane petrol and paraffin

Which one of the following situations is the correct one for measuring the normal 'in use' exhaust emissions from a petrol engine?
A = when the engine is cold
B = when the engine coolant water is hot and the sump oil is still cool
C = when the engine coolant water and sump oil are both at normal working temperature
D = when the air cleaner is removed and both the sump oil and engine water coolant are at working temperature

54. Which is the correct procedure when using an exhaust gas analyser for determining the exhaust emissions from a V6 petrol engine that has two totally separate exhaust systems?
A = add together the readings from each tail pipe
B = average the readings from the tail pipes
C = take the readings from only one tail pipe
D = multiply together the readings from each tail pipe

55. Which element in the atmosphere aids combustion?
A = Nitrogen
B = Carbon dioxide
C = Carbon monoxide
D = Oxygen

The color of the exhaust gas from a petrol engine that burns an excessive amount of lubricating sump oil is likely to?
A = blue
B = black
C = grey
D = white

Using ‘unleaded’ petrol engine designed only to use ‘leaded’ petrol is most likely to cause
A = valve and/ or valve seat problems
B = excessive carbon build up on pistons
C = excessive inlet manifold corrosion
D = the valve springs to weaken quicker than normal

An engine fitter with an exhaust system catalytic converter should not be run on ‘leaded petrol because?
A = The exhaust noise would not be properly silenced
B = the catalytic converter exterior casing would be harmed
C = The catalytic converter temperature would be too low
D = the catalalytic converter would probably be harmed internally

Which one of the following would INCREASE the co (carbon monoxide) content in the exhaust gases from a four cylinder petrol engine?
A = weakening the petrol/ air mixture
B = removing the air cleaner
C = restricting the air intake to the carburetor
D = running the engine on high octane fuel

A leaking exhaust analyzer probe will cause the emissions reading to be?
A = Lower for HC (hydrocarbon) than they really are.
B = higher for HC (hydrocarbon) than they really are
C = lower for O2 (oxygen) than they really are
D = higher for CO (carbon monoxide) than they really are.